Power metric optimization and uplink DM-RS design for LTE/LTE-A uplink transmissions in unlicensed spectrum

ABSTRACT

Methods and apparatus for wireless communication are described. A method may include receiving at a user equipment (UE) a number of allocated interlaces for an uplink transmission over a shared spectrum, each of which may include a plurality of non-contiguous resource blocks (RB) of the shared spectrum. In some cases, the number of allocated interlaces is unsupported by joint interlace precoding hardware of the UE and the allocated interlaces may be partitioned into subsets of interlaces which may be a size supported by the joint interlace precoding hardware. Reference signals may be generated for the RBs of the allocated interlaces according to a reference signal sequence based on an ordering of the RBs for the allocated interlaces within the shared spectrum.

CROSS REFERENCES

The present application for patent claims priority to U.S. ProvisionalPatent Application No. 61/911,342 by Yerramalli et al., entitled “PowerMetric Optimization And Uplink DM-RS Design For LTE/LTE-A UplinkTransmissions In Unlicensed Spectrum,” filed Dec. 3, 2013, assigned tothe assignee hereof, and expressly incorporated by reference herein.

BACKGROUND

Field of Disclosure

The following relates generally to wireless communication, and morespecifically to power metric optimization and uplink demodulationreference signal (DM-RS) design.

Description of Related Art

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing the available system resources (e.g., time, frequency, andpower). Examples of such multiple-access systems include code-divisionmultiple access (CDMA) systems, time-division multiple access (TDMA)systems, frequency-division multiple access (FDMA) systems, andorthogonal frequency-division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communications system may includea number of base stations, each simultaneously supporting communicationfor multiple mobile devices. Base stations may communicate with mobiledevices on downstream and upstream communication links.

The protocols or techniques used to transmit data or control signals(i.e., transmissions) over one or more communication links may have animpact on one or more power metrics (e.g., the peak-to-average powerratio (PAPR) or cubic metric (CM)) associated with the transmissions.For purposes such as power conservation and reliable transmissions, itmay be desirable to transmit data or control signals using protocols ortechniques that optimize these power metrics.

SUMMARY

The described features generally relate to methods and apparatus forwireless communication. The methods and apparatus may in some cases beused to optimize one or more power metrics (e.g., PAPR or CM) associatedwith uplink transmissions, such as LTE/LTE-A uplink transmissions inunlicensed spectrum. Some methods and apparatus may be more suited tooptimizing one or more power metrics applicable to data signals, whileother methods and apparatus may be more suited to optimizing one or morepower metrics applicable to control signals (e.g., reference signals).

In some examples, a method for wireless communication includes receivingat a user equipment (UE) a number of allocated interlaces for an uplinktransmission over a shared spectrum, wherein each allocated interlaceincludes a plurality of non-contiguous resource blocks of the sharedspectrum, and generating reference signals for the resource blocks ofthe allocated interlaces according to a reference signal sequence basedon an ordering of the resource blocks for the allocated interlaceswithin the shared spectrum.

In some examples, an apparatus for wireless communication includes aprocessor and memory coupled to the processor. The processor may beconfigured to receive at a user equipment (UE) a number of allocatedinterlaces for an uplink transmission over a shared spectrum, whereineach allocated interlace includes a plurality of non-contiguous resourceblocks of the shared spectrum, and generate reference signals for theresource blocks of the allocated interlaces according to a referencesignal sequence based on an ordering of the resource blocks for theallocated interlaces within the shared spectrum.

In some examples, a non-transitory computer-readable medium for storinginstructions executable by a processor includes instructions to receiveat a user equipment (UE) a number of allocated interlaces for an uplinktransmission over a shared spectrum, wherein each allocated interlaceincludes a plurality of non-contiguous resource blocks of the sharedspectrum, and instructions to generate reference signals for theresource blocks of the allocated interlaces according to a referencesignal sequence based on an ordering of the resource blocks for theallocated interlaces within the shared spectrum.

In some examples, a method for wireless communication includes receivingat a user equipment (UE) a number of allocated interlaces for an uplinktransmission over a shared spectrum, wherein each allocated interlaceincludes a plurality of non-contiguous resource blocks of the sharedspectrum, and wherein the number of allocated interlaces is unsupportedby joint interlace precoding hardware of the UE, partitioning theallocated interlaces into at least two subsets of interlaces, wherein asize of each subset of interlaces is supported by the joint interlaceprecoding hardware of the UE, and performing joint interlace precodingseparately on each subset of interlaces at the UE.

Various examples of the above-described methods, devices, ornon-transitory computer-readable medium may include the features of,means for, modules for, or processor-executable instructions fortransmitting the uplink transmission over the shared spectrum, whereinthe uplink transmission includes at least one of the allocatedinterlaces. Generating the reference signals may include mappingreference signal symbols from the reference signal sequence to theresource blocks of the allocated interlaces within the shared spectrumaccording to frequency, wherein a separate reference signal is generatedfor each of the resource blocks of the allocated interlaces based on thereference signal symbols mapped to that resource block. In some cases,the shared spectrum includes a plurality of resource blocks associatedwith at least one unallocated interlace, and generating the referencesignals may include mapping reference signal symbols from the referencesignal sequence to the resource blocks of the allocated interlace andthe at least one unallocated interlace according to frequency, andpuncturing the reference signal sequence to determine a subset ofreference signal symbols mapped to the resource blocks of the allocatedinterlaces, wherein a separate reference signal is generated for each ofthe resource blocks of the allocated interlaces based on the referencesignal symbols mapped to that resource block.

In some cases, generating the reference signals includes generating anumber of computer generated sequences, and mapping one of the computergenerated sequences to one of the resource blocks of the allocatedinterlaces within the shared spectrum. A length of the computergenerated sequences may be based at least in part on a number offrequency subcarriers for the resource blocks. The number of computergenerated sequences may be based at least in part on the number ofallocated interlaces. In some cases, mapping one of the computergenerated sequences to one of the resource blocks may include generatingan outer sequence, determining a number of combined sequences, whereinthe combined sequences are based at least in part on at least one of thecomputer generated sequences and the outer sequence, and mapping one ofthe combined sequences to one of the resource blocks of the allocatedinterlaces within the shared spectrum.

Various examples of the methods, devices, or non-transitorycomputer-readable medium may include the features of, means for, modulesfor, or processor-executable instructions for shifting at least one ofthe computer generated sequences based at least in part on a randomcyclic shift.

Various examples of the methods, devices, or non-transitorycomputer-readable medium may include the features of, means for, modulesfor, or processor-executable instructions for selecting the size of eachsubset of interlaces based on a power metric associated with acombination of the selected sizes for the UE. In some cases, the numberof allocated resources includes 7.

Various examples of the methods, devices, or non-transitorycomputer-readable medium may include the features of, means for, modulesfor, or processor-executable instructions for transmitting the subsetsof interlaces over the shared spectrum to a base station. In some cases,the at least two subsets of interlaces include a first set of oneinterlace and a second set of six interlaces.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the spirit and scope of the appended claims. Features whichare believed to be characteristic of the concepts disclosed herein, bothas to their organization and method of operation, together withassociated advantages will be better understood from the followingdescription when considered in connection with the accompanying figures.Each of the figures is provided for the purpose of illustration anddescription only, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the following drawings. In theappended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 shows a block diagram of a wireless communication system, inaccordance with various aspects of the present disclosure;

FIG. 2A shows a diagram that illustrates examples of deploymentscenarios for using LTE/LTE-A in unlicensed spectrum, in accordance withvarious aspects of the present disclosure;

FIG. 2B shows a wireless communication system that illustrates anexample of a standalone mode for LTE/LTE-A in unlicensed spectrum, inaccordance with various aspects of the present disclosure;

FIG. 3 shows a block diagram of an apparatus for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 4 shows a block diagram of a transmitter module for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 5 shows a block diagram of a transmitter module for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 6 shows a block diagram of an apparatus for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 7 shows a block diagram of an apparatus for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 8 is a flow chart illustrating an example of a method of wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 9 is a flow chart illustrating an example of a method of wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 10 is a flow chart illustrating an example of a method of wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 11 is a flow chart illustrating an example of a method of wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 12 illustrates an example of how allocated interlaces may bepartitioned for the purpose of performing joint interlace precodingusing joint interlace precoding hardware configured for LTE/LTE-Acommunications, in accordance with various aspects of the presentdisclosure;

FIG. 13 shows a block diagram of an apparatus for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 14 is a flow chart illustrating an example of a method of wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 15 illustrates an example of how a reference signal (e.g., ademodulation reference signal (DM-RS)) may be generated for eachresource block of a number of allocated interlaces for an uplinktransmission over a shared spectrum, in accordance with various aspectsof the present disclosure;

FIG. 16 illustrates another example of how a reference signal (e.g., aDM-RS) may be generated for each resource block (RB) of a number ofallocated interlaces for an uplink transmission over a shared spectrum,in accordance with various aspects of the present disclosure;

FIG. 17 shows a block diagram of an apparatus for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 18 is a flow chart illustrating an example of a method of wirelesscommunication, in accordance with various aspects of the presentdisclosure;

FIG. 19 illustrates an example of how a plurality of resource elementspositions in a subframe may be mapped to a plurality of DM-RStransmissions over a shared spectrum, in accordance with various aspectsof the present disclosure;

FIG. 20 shows a block diagram of an apparatus for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure; and

FIG. 21 is a flow chart illustrating an example of a method of wirelesscommunication, in accordance with various aspects of the presentdisclosure.

DETAILED DESCRIPTION

When making 3GPP “Long Term Evolution” (LTE) or “LTE-Advanced” (LTE-A)uplink transmissions in unlicensed spectrum (e.g., a spectrum sharedwith apparatuses operating under LTE/LTE-A or other transmissionprotocols), it may be desirable to make an LTE/LTE-A uplink transmissionin such a manner that it occupies at least eighty percent (80%) of theavailable bandwidth of the unlicensed spectrum. One way to achieve the80% bandwidth occupancy requirement is to make an LTE/LTE-A uplinktransmission across one or more interlaces. An interlace is definedherein as a plurality of non-contiguous resource blocks. The pluralityof non-contiguous resource blocks may be selected in such a manner thatthe resource blocks span at least 80% of the available bandwidth of theunlicensed spectrum.

A problem that may be encountered when making an uplink transmissionacross one or more interlaces is poor power performance (e.g., high PAPRor high CM). The techniques disclosed herein therefore provide ways toreduce or optimize power metrics such as PAPR and CM when makingLTE/LTE-A uplink transmissions in unlicensed spectrum. The techniquesmay be particularly applicable to SC-FDMA-based transmissions. Thetechniques may also be applied to LTE/LTE-A uplink transmissions inlicensed spectrum, though such an application may not be backwardcompatible with existing LTE/LTE-A standards.

The techniques described herein are not limited to LTE/LTE-A, and mayalso be used for various wireless communication systems such as CDMA,TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms “system” and“network” are often used interchangeably. A CDMA system may implement aradio technology such as CDMA2000, Universal Terrestrial Radio Access(UTRA), etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards.IS-2000 Releases 0 and A are commonly referred to as CDMA2000 1×, 1×,etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1×EV-DO, HighRate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) andother variants of CDMA. A TDMA system may implement a radio technologysuch as Global System for Mobile Communications (GSM). An OFDMA systemmay implement a radio technology such as Ultra Mobile Broadband (UMB),Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal MobileTelecommunication System (UMTS). LTE and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, andGSM are described in documents from an organization named “3rdGeneration Partnership Project” (3GPP). CDMA2000 and UMB are describedin documents from an organization named “3rd Generation PartnershipProject 2” (3GPP2). The techniques described herein may be used for thesystems and radio technologies mentioned above as well as other systemsand radio technologies. The description below, however, describes an LTEsystem for purposes of example, and LTE terminology is used in much ofthe description below, although the techniques are applicable beyond LTEapplications.

The following description provides examples, and is not limiting of thescope, applicability, or configuration set forth in the claims. Changesmay be made in the function and arrangement of elements discussedwithout departing from the spirit and scope of the disclosure. Variousexamples may omit, substitute, or add various procedures or componentsas appropriate. For instance, the methods described may be performed inan order different from that described, and various steps may be added,omitted, or combined. Also, features described with respect to certainexamples may be combined in other examples.

FIG. 1 shows a block diagram of a wireless communications system 100, inaccordance with various aspects of the present disclosure. The wirelesscommunications system 100 includes a plurality of base stations 105(e.g., eNBs, WLAN access points, or other access points), a number ofuser equipments (UEs) 115, and a core network 130. Some of the basestations 105 may communicate with the UEs 115 under the control of abase station controller (not shown), which may be part of the corenetwork 130 or certain ones of the base stations 105 in variousexamples. Some of the base stations 105 may communicate controlinformation or user data with the core network 130 through backhaul 132.In some examples, some of the base stations 105 may communicate, eitherdirectly or indirectly, with each other over backhaul links 134, whichmay be wired or wireless communication links. The wirelesscommunications system 100 may support operation on multiple carriers(waveform signals of different frequencies). Multi-carrier transmitterscan transmit modulated signals simultaneously on the multiple carriers.For example, each communications link 125 may be a multi-carrier signalmodulated according to various radio technologies. Each modulated signalmay be sent on a different carrier and may carry control information(e.g., reference signals, control channels, etc.), overhead information,data, etc.

The base stations 105 may wirelessly communicate with the UEs 115 viaone or more access point antennas. Each of the base stations 105 mayprovide communication coverage for a respective coverage area 110. Insome examples, a base station 105 may be referred to as an access point,a base transceiver station (BTS), a radio base station, a radiotransceiver, a basic service set (BSS), an extended service set (ESS), aNodeB, an evolved NodeB (eNB), a Home NodeB, a Home eNodeB, a WLANaccess point, a WiFi node or some other suitable terminology. Thecoverage area 110 for an access point may be divided into sectors makingup only a portion of the coverage area (not shown). The wirelesscommunications system 100 may include base stations 105 of differenttypes (e.g., macro, micro, or pico base stations). The base stations 105may also utilize different radio technologies, such as cellular or WLANradio access technologies. The base stations 105 may be associated withthe same or different access networks or operator deployments. Thecoverage areas of different base stations 105, including the coverageareas of the same or different types of base stations 105, utilizing thesame or different radio technologies, or belonging to the same ordifferent access networks, may overlap.

In some examples, the wireless communications system 100 may include anLTE/LTE-A communications system (or network), which LTE/LTE-Acommunications system may support one or more modes of operation ordeployment in unlicensed spectrum. In other examples, the wirelesscommunications system 100 may support wireless communication usingaccess technology different from LTE/LTE-A. In LTE/LTE-A communicationssystems, the term evolved NodeB or eNB may be generally used to describethe base stations 105.

The wireless communications system 100 may be a Heterogeneous LTE/LTE-Anetwork in which different types of base stations 105 provide coveragefor various geographical regions. For example, each base station 105 mayprovide communication coverage for a macro cell, a pico cell, a femtocell, or other types of cell. Small cells such as pico cells, femtocells, or other types of cells may include low power nodes or LPNs. Amacro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEswith service subscriptions with the network provider. A pico cell wouldgenerally cover a relatively smaller geographic area and may allowunrestricted access by UEs with service subscriptions with the networkprovider. A femto cell would also generally cover a relatively smallgeographic area (e.g., a home) and, in addition to unrestricted access,may also provide restricted access by UEs having an association with thefemto cell (e.g., UEs in a closed subscriber group (CSG), UEs for usersin the home, and the like). An eNB for a macro cell may be referred toas a macro eNB. An eNB for a pico cell may be referred to as a pico eNB.And, an eNB for a femto cell may be referred to as a femto eNB or a homeeNB. An eNB may support one or multiple (e.g., two, three, four, and thelike) cells.

The core network 130 may communicate with the base stations 105 via abackhaul 132 (e.g., S1 application protocol, etc.). The base stations105 may also communicate with one another, e.g., directly or indirectlyvia backhaul links 134 (e.g., X2 application protocol, etc.) or viabackhaul 132 (e.g., through core network 130). The wirelesscommunications system 100 may support synchronous or asynchronousoperation. For synchronous operation, the eNBs may have similar frame orgating timing, and transmissions from different eNBs may beapproximately aligned in time. For asynchronous operation, the eNBs mayhave different frame or gating timing, and transmissions from differenteNBs may not be aligned in time. The techniques described herein may beused for either synchronous or asynchronous operations.

The UEs 115 may be dispersed throughout the wireless communicationssystem 100, and each UE 115 may be stationary or mobile. A UE 115 mayalso be referred to by those skilled in the art as a mobile device, amobile station, a subscriber station, a mobile unit, a subscriber unit,a wireless unit, a remote unit, a wireless device, a wirelesscommunication device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a user agent, a mobile client, a client, or someother suitable terminology. A UE 115 may be a cellular phone, a personaldigital assistant (PDA), a wireless modem, a wireless communicationdevice, a handheld device, a tablet computer, a laptop computer, acordless phone, a wearable item such as a watch or glasses, a wirelesslocal loop (WLL) station, or the like. A UE 115 may be able tocommunicate with macro eNBs, pico eNBs, femto eNBs, relays, and thelike. A UE 115 may also be able to communicate over different accessnetworks, such as cellular or other WWAN access networks, or WLAN accessnetworks.

The communications links 125 shown in wireless communications system 100may include uplinks for carrying uplink (UL) transmissions (e.g., from aUE 115 to a base station 105) or downlinks for carrying downlink (DL)transmissions (e.g., from a base station 105 to a UE 115). The ULtransmissions may also be called reverse link transmissions, while theDL transmissions may also be called forward link transmissions. Thedownlink transmissions may be made using a licensed spectrum, anunlicensed spectrum, or both. Similarly, the uplink transmissions may bemade using a licensed spectrum, an unlicensed spectrum, or both.

In some examples of the wireless communications system 100, variousdeployment scenarios for LTE/LTE-A in unlicensed spectrum may besupported, including a supplemental downlink mode in which LTE/LTE-Adownlink capacity in a licensed spectrum may be offloaded to anunlicensed spectrum, a carrier aggregation mode in which both LTE/LTE-Adownlink and uplink capacity may be offloaded from a licensed spectrumto an unlicensed spectrum, and a standalone mode in which LTE/LTE-Adownlink and uplink communications between a base station (e.g., eNB)and a UE may take place in an unlicensed spectrum. Base stations 105 aswell as UEs 115 may support one or more of these or similar modes ofoperation. OFDMA communications signals may be used in thecommunications links 125 for LTE/LTE-A downlink transmissions in anunlicensed or a licensed spectrum, while SC-FDMA communications signalsmay be used in the communications links 125 for LTE/LTE-A uplinktransmissions in an unlicensed or a licensed spectrum.

When a UE 115 is configured to transmit uplink communications over anunlicensed or shared spectrum, the UE may be allocated (e.g., by a basestation 105) one or more interlaces of the unlicensed or shared spectrumfor the uplink transmissions. Each of the interlaces may includemultiple non-contiguous resource blocks of the unlicensed or sharedspectrum. The UE 115 may generate reference signals (e.g., demodulationreference signals (DMRS)) for the resource blocks of the allocatedinterlaces according to a reference signal sequence. The referencesignal sequence may be based on an ordering of the resource blocks forthe allocated interlaces within the unlicensed or shared spectrum. Byselecting the reference signal sequence on a per-resource block basis,the reference signals may improve per-resource block narrow band channelestimation by a base station 105, thereby resulting in an overallreduction of power and PAPR.

FIG. 2A shows a diagram that illustrates examples of deploymentscenarios for using LTE in an unlicensed spectrum, in accordance withvarious aspects of the present disclosure. In one example, FIG. 2Aillustrates a wireless communications system 200 illustrating examplesof a supplemental downlink mode and a carrier aggregation mode for anLTE/LTE-A network that supports deployment in unlicensed spectrum. Thewireless communications system 200 may be an example of portions of thewireless communications system 100 of FIG. 1. Moreover, the base station205 may be an example of the base stations 105 of FIG. 1, while the UEs215, 215-a, and 215-b may be examples of the UEs 115 of FIG. 1.

In the example of a supplemental downlink mode in the wirelesscommunications system 200, the base station 205 may transmit OFDMAcommunications signals to a UE 215 using a downlink 220. The downlink220 may be associated with a frequency F1 in an unlicensed spectrum. Thebase station 205 may transmit OFDMA communications signals to the sameUE 215 using a bidirectional link 225 and may receive SC-FDMAcommunications signals from that UE 215 using the bidirectional link225. The bidirectional link 225 may be associated with a frequency F4 ina licensed spectrum. The downlink 220 in the unlicensed spectrum and thebidirectional link 225 in the licensed spectrum may operateconcurrently. The downlink 220 may provide a downlink capacity offloadfor the base station 205. In some examples, the downlink 220 may be usedfor unicast services (e.g., addressed to one UE) or for multicastservices (e.g., addressed to several UEs). This scenario may occur withany service provider (e.g., traditional mobile network operator (MNO))that uses a licensed spectrum and needs to relieve some of the trafficor signaling congestion.

In one example of a carrier aggregation mode in the wirelesscommunications system 200, the base station 205 may transmit OFDMAcommunications signals to a UE 215-a using a bidirectional link 230 andmay receive SC-FDMA communications signals from the same UE 215-a usingthe bidirectional link 230. The bidirectional link 230 may be associatedwith the frequency F1 in the unlicensed spectrum. The base station 205may also transmit OFDMA communications signals to the same UE 215-ausing a bidirectional link 235 and may receive SC-FDMA communicationssignals from the same UE 215-a using the bidirectional link 235. Thebidirectional link 235 may be associated with a frequency F2 in alicensed spectrum. The bidirectional link 230 may provide a downlink anduplink capacity offload for the base station 205. Like the supplementaldownlink described above, this scenario may occur with any serviceprovider (e.g., MNO) that uses a licensed spectrum and needs to relievesome of the traffic or signaling congestion.

In another example of a carrier aggregation mode in the wirelesscommunications system 200, the base station 205 may transmit OFDMAcommunications signals to a UE 215-b using a bidirectional link 240 andmay receive SC-FDMA communications signals from the same UE 215-b usingthe bidirectional link 240. The bidirectional link 240 may be associatedwith a frequency F3 in an unlicensed spectrum. The base station 205 mayalso transmit OFDMA communications signals to the same UE 215-b using abidirectional link 245 and may receive SC-FDMA communications signalsfrom the same UE 215-b using the bidirectional link 245. Thebidirectional link 245 may be associated with the frequency F2 in thelicensed spectrum. The bidirectional link 240 may provide a downlink anduplink capacity offload for the base station 205. This example and thoseprovided above are presented for illustrative purposes and there may beother similar modes of operation or deployment scenarios that combineLTE/LTE-A in licensed and unlicensed spectrum for capacity offload.

As described above, the typical service provider that may benefit fromthe capacity offload offered by using LTE/LTE-A in unlicensed spectrumis a traditional MNO with LTE/LTE-A spectrum. For these serviceproviders, an operational configuration may include a bootstrapped mode(e.g., supplemental downlink, carrier aggregation) that uses theLTE/LTE-A primary component carrier (PCC) on the licensed spectrum and asecondary component carrier (SCC) on the unlicensed spectrum.

In the carrier aggregation mode, data and control may generally becommunicated in the licensed spectrum (e.g., bidirectional links 225,235, and 245) while data may generally be communicated in the unlicensedspectrum (e.g., bidirectional links 230 and 240). The carrieraggregation mechanisms supported when using unlicensed spectrum may fallunder a hybrid frequency division duplexing-time division duplexing(FDD-TDD) carrier aggregation or a TDD-TDD carrier aggregation withdifferent symmetry across component carriers.

FIG. 2B shows a wireless communication system 250 that illustrates anexample of a standalone mode for LTE/LTE-A in unlicensed spectrum, inaccordance with various aspects of the present disclosure. The wirelesscommunication system 250 may be an example of portions of the wirelesscommunications system 100 of FIG. 1 or 200 of FIG. 2A. Moreover, thebase station 205 may be an example of the base stations 105 or 205described with reference to FIG. 1 or 2A, while the UE 215-c may be anexample of the UEs 115 or 215 of FIG. 1 or 2A.

In the example of a standalone mode in the wireless communication system250, the base station 205 may transmit OFDMA communications signals tothe UE 215-c using a bidirectional link 255 and may receive SC-FDMAcommunications signals from the UE 215-c using the bidirectional link255. The bidirectional link 255 may be associated with the frequency F3in an unlicensed spectrum described above with reference to FIG. 2A. Thestandalone mode may be used in non-traditional wireless accessscenarios, such as in-stadium access (e.g., unicast, multicast). Thetypical service provider for this mode of operation may be a stadiumowner, cable company, event host, hotel, enterprise, or largecorporation that does not have licensed spectrum.

In some examples, a transmitting device such as a base station 105, 205(e.g., an eNB) described with reference to FIG. 1, 2A, or 2B, or a UE115 or 215 described with reference to FIG. 1, 2A, or 2B, may use agating interval to gain access to a channel of the shared spectrum(e.g., to a physical channel of the licensed or unlicensed spectrum).The gating interval may define the application of a contention-basedprotocol, such as a Listen Before Talk (LBT) protocol based on the LBTprotocol specified in ETSI (EN 301 893). When using a gating intervalthat defines the application of an LBT protocol, the gating interval mayindicate when a transmitting device needs to perform a Clear ChannelAssessment (CCA). The outcome of the CCA may indicate to thetransmitting device whether a channel of the shared unlicensed spectrumis available or in use. When the CCA indicates that the channel isavailable (e.g., “clear” for use), the gating interval may allow thetransmitting device to use the channel—typically for a predefinedtransmission interval. When the CCA indicates that the channel is notavailable (e.g., in use or reserved), the gating interval may preventthe transmitting device from using the channel during the transmissioninterval.

In some cases, it may be useful for a transmitting device to generate agating interval on a periodic basis and synchronize at least oneboundary of the gating interval with at least one boundary of a periodicframe structure. For example, it may be useful to generate a periodicgating interval for a cellular downlink in a shared spectrum, and tosynchronize at least one boundary of the periodic gating interval withat least one boundary of a periodic frame structure (e.g., LTE/LTE-Aradio frame) associated with the cellular downlink.

FIG. 3 shows a block diagram 300 of an apparatus 315 for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure. In some examples, the apparatus 315 may be an example of oneor more aspects of one of the UEs 115 or 215 described with reference toFIG. 1, 2A, or 2B. The apparatus 315 may also be a processor. Theapparatus 315 may include a receiver module 310, a wirelesscommunication management module 320, or a transmitter module 330. Eachof these components may be in communication with each other.

The components of the apparatus 315 may, individually or collectively,be implemented using one or more application-specific integratedcircuits (ASICs) adapted to perform some or all of the applicablefunctions in hardware. Alternatively, the functions may be performed byone or more other processing units (or cores), on one or more integratedcircuits. In other examples, other types of integrated circuits may beused (e.g., Structured/Platform ASICs, Field Programmable Gate Arrays(FPGAs), and other Semi-Custom ICs), which may be programmed in anymanner known in the art. The functions of each unit may also beimplemented, in whole or in part, with instructions embodied in amemory, formatted to be executed by one or more general orapplication-specific processors.

In some examples, the receiver module 310 may be or include a radiofrequency (RF) receiver, such as an RF receiver operable to receivetransmissions in a first spectrum (e.g., an LTE/LTE-A licensed spectrum)or a second spectrum (e.g., an LTE/LTE-A unlicensed spectrum, whichunlicensed spectrum may be shared with one or more apparatuses operatingunder the same or different transmission protocols, and which unlicensedspectrum may include WiFi spectrum). The receiver module 310 may be usedto receive various types of data or control signals (i.e.,transmissions) over one or more communication links of a wirelesscommunications system including the first and second spectrums, such asone or more communication links of the wireless communications system100, 200, or 250 described with reference to FIG. 1, 2A, or 2B.

In some examples, the transmitter module 330 may be or include an RFtransmitter, such as an RF transmitter operable to transmit in the firstspectrum or the second spectrum. The transmitter module 330 may be usedto transmit various types of data or control signals (i.e.,transmissions) over one or more communication links of the wirelesscommunications system including the first spectrum and the secondspectrum.

In some examples, the wireless communication management module 320 maymanage the receipt of wireless communications via the receiver module310 or the transmission of wireless communications via the transmittermodule 330. On the transmission side, and by way of example, thewireless communication management module 320 may manage transmissionsfor the purpose of managing peak-to-average power ratio (PAPR), cubicmetric (CM), or other power metrics pertaining to transmissions from thetransmitter module 330. In some cases, the wireless communicationmanagement module 320 may select a permutation to apply to a stream ofbits or modulation symbols, which permutation optimizes one or morepower metrics associated with the stream. In other cases, the wirelesscommunication management module 320 may manage the precoding ofinterlaces or select parameters used to transmit one or more referencesymbols associated with a stream of bits or modulation symbols.

FIG. 4 shows a block diagram 400 of a transmitter module 430 for use inwireless communication, in accordance with various aspects of thepresent disclosure. In some examples, the transmitter module 430 may bean example of a transmitter module included in one or more of the UEs115 or 215 described with reference to FIG. 1, 2A, or 2B. Thetransmitter module 430 may also be an example of one or more aspects ofthe transmitter module 330 described with reference to FIG. 3. Thetransmitter module 430 may include a plurality of (e.g., two or more)separate transmit chain branches 435, 440, or 445.

The components of the transmitter module 430 may, individually orcollectively, be implemented using one or more ASICs adapted to performsome or all of the applicable functions in hardware. Alternatively, thefunctions may be performed by one or more other processing units (orcores), on one or more integrated circuits. In other examples, othertypes of integrated circuits may be used (e.g., Structured/PlatformASICs, FPGAs, and other Semi-Custom ICs), which may be programmed in anymanner known in the art. The functions of each unit may also beimplemented, in whole or in part, with instructions embodied in amemory, formatted to be executed by one or more general orapplication-specific processors.

In some examples, the separate transmit chain branches 435, 440, 445 mayeach receive a stream of bits or modulation symbols 450 and have an endcoupled to a transmit chain branch selector 455 that outputs a stream ofbits or modulation symbols generated by a selected one of the separatetransmit chain branches 535, 540, 545. In some cases, the transmit chainbranch selector 455 may select one of the transmit chain branches 435,440, 445 based on respective estimated power metrics of the transmitchain branches 435, 440, 445. For example, the transmit chain branchselector 455 may select one of the transmit chain branches 435, 440, 445having a PAPR or CM that satisfies a threshold (e.g., is less than athreshold), or the transmit chain branch selector 455 may select one ofthe transmit chain branches 435, 440, 445 associated with a lowest PAPRor CM. The transmit chain branch selector 455 may in some cases beoperated under control of the wireless communication management module320 described with reference to FIG. 3.

In some examples, one of the transmit chain branches 435, 440, 445 maybe selected for at least one of a slot, a subframe, or other block ofbits or modulation symbols of the stream. In these examples, therespective estimated power metrics of the transmit chain branches 435,440, 445 may include respective estimated power metrics across all bitsor modulation symbols in the slot, subframe, or other block of bits ormodulation symbols.

FIG. 5 shows a block diagram 500 of a transmitter module 530 for use inwireless communication, in accordance with various aspects of thepresent disclosure. In some examples, the transmitter module 530 may bean example of a transmitter module included in one or more of the UEs115 or 215 described with reference to FIG. 1, 2A, or 2B. Thetransmitter module 530 may also be an example of one or more aspects ofthe transmitter module 330 or 430 described with reference to FIG. 3 or4. The transmitter module 530 may include a plurality of (e.g., two ormore) separate transmit chain branches 535, 540, or 545.

The components of the transmitter module 530 may, individually orcollectively, be implemented using one or more ASICs adapted to performsome or all of the applicable functions in hardware. Alternatively, thefunctions may be performed by one or more other processing units (orcores), on one or more integrated circuits. In other examples, othertypes of integrated circuits may be used (e.g., Structured/PlatformASICs, FPGAs, and other Semi-Custom ICs), which may be programmed in anymanner known in the art. The functions of each unit may also beimplemented, in whole or in part, with instructions embodied in amemory, formatted to be executed by one or more general orapplication-specific processors.

In some examples, the separate transmit chain branches 535, 540, 545 mayeach receive a stream of bits or modulation symbols 550, permute thestream of bits or modulation symbols 550 in one of a number of differentways at a respective permutation module 560, 562, or 564, and thenprocess the permutated stream of bits or modulation symbols through asimilar chain of processing modules including, for example, a respectiveDiscrete Fourier Transform (DFT) precoding module 570, 572, or 574, arespective subcarrier mapping module 580, 582, or 584, or a respectiveInverse DFT (IDFT) module 590, 592, or 594. The end of each of theseparate transmit chain branches 535, 540, 545 may be coupled to atransmit chain branch selector 555 that outputs a stream of bits ormodulation symbols generated by a selected one of the separate transmitchain branches 535, 540, 545. In some cases, the transmit chain branchselector 555 may select one of the transmit chain branches 535, 540, 545based on respective estimated power metrics of the transmit chainbranches 535, 540, 545. For example, the transmit chain branch selector555 may select one of the transmit chain branches 535, 540, 545 having aPAPR or CM that satisfies a threshold (e.g., is less than a threshold),or the transmit chain branch selector 555 may select one of the transmitchain branches 535, 540, 545 associated with a lowest PAPR or CM. Thetransmit chain branch selector 555 may in some cases be operated undercontrol of the wireless communication management module 320 describedwith reference to FIG. 3.

In some cases, the transmit chain branch selector 555 may select one ofthe transmit chain branches based on an estimated power metric of one ofthe transmit chain branches 535, 540, 545 (or an estimated power metricof one of the permutations processed by one of the transmit chainbranches 535, 540, 545) satisfying a threshold. For example, thetransmit chain branch selector 555 may serially or in parallel comparethe estimated power metric of each transmit chain branch 535, 540, 545to a threshold, and upon identifying an estimated power metric thatsatisfies a threshold, select the transmit chain branch 535, 540, or 545that corresponds to the identified estimated power metric. Thecomparison(s) of other estimated power metrics to the threshold may insome cases be skipped or terminated upon identifying a first estimatedpower metric to satisfy the threshold.

In other cases, the transmit chain branch selector 555 may select one ofthe transmit chain branches based on a comparison of respectiveestimated power metrics of the transmit chain branches 535, 540, 545 (ora comparison of respective estimated power metrics of the permutationsprocessed by the transmit chain branches 535, 540, 545) at ends of theseparate transmit chain branches (e.g., to identify an optimal one ofthe estimated power metrics).

In other cases, the transmit chain branch selector 555 may select one ofthe transmit chain branches based on a comparison of respectiveestimated power metrics of the transmit chain branches 535, 540, 545 (ora comparison of respective estimated power metrics of the permutationsprocessed by the transmit chain branches 535, 540, 545) at anintermediate point during the processing of the permutations at theseparate transmit chain branches (e.g., to identify an optimal one ofthe estimated power metrics). By way of example, the transmitter module530 includes two intermediate points, each of which is denoted by abranch elimination module 510 or 520. Upon selecting a transmit chainbranch 535, 540, 545 or permutation at one of the intermediate points,processing of the non-selected permutations may be discontinued, whileprocessing of the selected permutation may continue.

FIG. 6 shows a block diagram 600 of an apparatus 615 for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure. In some examples, the apparatus 615 may be an example of oneor more aspects of one of the UEs 115 or 215 described with reference toFIG. 1, 2A, or 2B, or the apparatus 315 described with reference to FIG.3. The apparatus 615 may also be a processor. The apparatus 615 mayinclude a receiver module 610, a wireless communication managementmodule 620, or a transmitter module 630. Each of these components may bein communication with each other.

The components of the apparatus 615 may, individually or collectively,be implemented using one or more ASICs adapted to perform some or all ofthe applicable functions in hardware. Alternatively, the functions maybe performed by one or more other processing units (or cores), on one ormore integrated circuits. In other examples, other types of integratedcircuits may be used (e.g., Structured/Platform ASICs, FPGAs, and otherSemi-Custom ICs), which may be programmed in any manner known in theart. The functions of each unit may also be implemented, in whole or inpart, with instructions embodied in a memory, formatted to be executedby one or more general or application-specific processors.

In some examples, the receiver module 610 may be or include a radiofrequency (RF) receiver, such as an RF receiver operable to receivetransmissions in a first spectrum (e.g., an LTE/LTE-A licensed spectrum)or a second spectrum (e.g., an LTE/LTE-A unlicensed spectrum, whichunlicensed spectrum may be shared with one or more apparatuses operatingunder the same or different transmission protocols, and which unlicensedspectrum may include WiFi spectrum). The RF receiver may includeseparate receivers for the first spectrum and the second spectrum. Theseparate receivers may in some cases take the form of a licensedspectrum receiver module 612 for communicating over the first spectrum,and an unlicensed spectrum receiver module 614 for communicating overthe second spectrum. The receiver module 610, including the licensedspectrum receiver module 612 or the unlicensed spectrum receiver module614, may be used to receive various types of data or control signals(i.e., transmissions) over one or more communication links of a wirelesscommunications system including the first and second spectrums, such asone or more communication links of the wireless communications system100, 200, or 250 described with reference to FIG. 1, 2A, or 2B.

In some examples, the transmitter module 630 may be or include an RFtransmitter, such as an RF transmitter operable to transmit in the firstspectrum or the second spectrum. The RF transmitter may include separatetransmitters for the first spectrum and the second spectrum. Theseparate transmitters may in some cases take the form of a licensedspectrum transmitter module 632 for communicating over the firstspectrum, and an unlicensed spectrum transmitter module 634 forcommunicating over the second spectrum. In some cases, the unlicensedspectrum transmitter module 634 may be configured similarly to thetransmitter module 430 or 530 described with reference to FIG. 4 or 5.The transmitter module 630, including the licensed spectrum transmittermodule 632 or the unlicensed spectrum transmitter module 634, may beused to transmit various types of data or control signals (i.e.,transmissions) over one or more communication links of the wirelesscommunications system including the first spectrum and the secondspectrum.

In some examples, the wireless communication management module 620 maybe an example of one or more aspects of the wireless communicationmanagement module 320 described with reference to FIG. 3 and may includea permutation generation module 635, a permutation association module640, or a permutation selection module 645. Each of these components maybe in communication with each other.

In some examples, the permutation generation module 635 may be used toreceive a stream of bits or modulation symbols and generate a pluralityof different permutations of the stream of bits or modulation symbols.The stream of bits or modulation symbols may in some cases be used forSC-FDMA-based transmissions on an LTE/LTE-A uplink channel in licensedor unlicensed spectrum.

In some examples, the permutation association module 640 may be used toassociate each of the permutations generated by the permutationgeneration module 635 with a separate transmit chain branch of theunlicensed spectrum transmitter module 634.

In some examples, the permutation selection module 645 may be used toselect one of the permutations for transmission from the unlicensedspectrum transmitter module 634. The one of the permutations may beselected based on respective estimated power metrics (e.g., PAPR or CM)of the permutations.

The permutation selection module 645 may in some cases select the one ofthe permutations for at least one of a slot, a subframe, or other blockof bits or modulation symbols of the stream. In these cases, therespective estimated power metrics of the permutations may includerespective estimated power metrics across all bits or modulation symbolsin the slot, subframe, or other block of bits or modulation symbols.

FIG. 7 shows a block diagram 700 of an apparatus 715 for use in wirelesscommunication, in accordance with various aspects of the presentdisclosure. In some examples, the apparatus 715 may be an example of oneor more aspects of one of the UEs 115 or 215 described with reference toFIG. 1, 2A, or 2B, or one of the apparatuses 315 or 615 described withreference to FIG. 3 or 6. The apparatus 715 may also be a processor. Theapparatus 715 may include a receiver module 710, a wirelesscommunication management module 720, or a transmitter module 730. Eachof these components may be in communication with each other.

The components of the apparatus 715 may, individually or collectively,be implemented using one or more ASICs adapted to perform some or all ofthe applicable functions in hardware. Alternatively, the functions maybe performed by one or more other processing units (or cores), on one ormore integrated circuits. In other examples, other types of integratedcircuits may be used (e.g., Structured/Platform ASICs, FPGAs, and otherSemi-Custom ICs), which may be programmed in any manner known in theart. The functions of each unit may also be implemented, in whole or inpart, with instructions embodied in a memory, formatted to be executedby one or more general or application-specific processors.

In some examples, the receiver module 710 may be or include a radiofrequency (RF) receiver, such as an RF receiver operable to receivetransmissions in a first spectrum (e.g., an LTE/LTE-A licensed spectrum)or a second spectrum (e.g., an LTE/LTE-A unlicensed spectrum, whichunlicensed spectrum may be shared with one or more apparatuses operatingunder the same or different transmission protocols, and which unlicensedspectrum may include WiFi spectrum). The RF receiver may includeseparate receivers for the first spectrum and the second spectrum. Theseparate receivers may in some cases take the form of a licensedspectrum receiver module 712 for communicating over the first spectrum,and an unlicensed spectrum receiver module 714 for communicating overthe second spectrum. The receiver module 710, including the licensedspectrum receiver module 712 or the unlicensed spectrum receiver module714, may be used to receive various types of data or control signals(i.e., transmissions) over one or more communication links of a wirelesscommunications system including the first and second spectrums, such asone or more communication links of the wireless communications system100, 200, or 250 described with reference to FIG. 1, 2A, or 2B.

In some examples, the transmitter module 730 may be or include an RFtransmitter, such as an RF transmitter operable to transmit in the firstspectrum or the second spectrum. The RF transmitter may include separatetransmitters for the first spectrum and the second spectrum. Theseparate transmitters may in some cases take the form of a licensedspectrum transmitter module 732 for communicating over the firstspectrum, and an unlicensed spectrum transmitter module 734 forcommunicating over the second spectrum. In some cases, the unlicensedspectrum transmitter module 734 may be configured similarly to thetransmitter module 430 or 530 described with reference to FIG. 4 or 5.The transmitter module 730, including the licensed spectrum transmittermodule 732 or the unlicensed spectrum transmitter module 734, may beused to transmit various types of data or control signals (i.e.,transmissions) over one or more communication links of the wirelesscommunications system including the first spectrum and the secondspectrum.

In some examples, the wireless communication management module 720 maybe an example of one or more aspects of the wireless communicationmanagement module 320 or 620 described with reference to FIG. 3 or 6 andmay include a permutation generation module 735, a permutationassociation module 740, a permutation selection module 745, or apermutation communication module 750. Each of these components may be incommunication with each other.

In some examples, the permutation generation module 735 may be used toreceive a stream of bits or modulation symbols and generate a pluralityof different permutations of the stream of bits or modulation symbols.The stream of bits or modulation symbols may in some cases be used forSC-FDMA-based transmissions on an LTE/LTE-A uplink channel in licensedor unlicensed spectrum.

The permutation generation module 735 may in some cases generate theplurality of different permutations of the stream by multiplying thestream by a multiplier derived from at least one pseudo-random sequence.The pseudo-random sequence may be known to both the apparatus 715 (or tothe unlicensed spectrum transmitter module 734 of the apparatus 715) andto a receiver communicatively coupled to the apparatus 715 (or to theunlicensed spectrum transmitter module 734 of the apparatus 715).

In some examples, the permutation association module 740 may be used toassociate each of the permutations generated by the permutationgeneration module 735 with a separate transmit chain branch of theunlicensed spectrum transmitter module 734. The permutations may then beprocessed at the separate transmit chain branches.

In some examples, the permutation selection module 745 may be used toselect one of the permutations for transmission from the unlicensedspectrum transmitter module 734. The one of the permutations may beselected based on respective estimated power metrics (e.g., PAPR or CM)of the permutations. The permutation selection module 745 may in somecases include an estimated power metric acquisition module 755 or anestimated power metric comparison module 760. The estimated power metricacquisition module 755 may be used to acquire the respective estimatedpower metrics of the permutations (e.g., from the separate transmitchain branches of the unlicensed spectrum transmitter module 734). Therespective estimated power metrics may be acquired at ends of theseparate transmit chain branches of the unlicensed spectrum transmittermodule 734 or at one or more intermediate points during the processingof the permutations at the separate transmit chain branches of theunlicensed spectrum transmitter module 734.

Upon the estimated power metric acquisition module 755 acquiringrespective estimated power metrics for the permutations processed at theseparate transmit chain branches of the unlicensed spectrum transmittermodule 734, the estimated power metric comparison module 760 may compareeach of the estimated power metrics to a threshold, to determine whetherone or more of the estimated power metrics satisfies the threshold. Forexample, the estimated power metric comparison module 760 may seriallyor in parallel compare the estimated power metric of each permutation toa threshold, and upon identifying an estimated power metric thatsatisfies the threshold, the permutation selection module 745 may selectthat permutation that corresponds to the identified estimated powermetric for transmission from the unlicensed spectrum transmitter module734. The comparison(s) of other estimated power metrics to the thresholdmay in some cases be skipped or terminated upon identifying a firstestimated power metric to satisfy the threshold. When the estimatedpower metrics are acquired at the ends of the separate transmit chainbranches, and when none of the estimated power metrics satisfies thethreshold, the permutation selection module 745 may select one of thepermutations for transmission from the unlicensed spectrum transmittermodule 734 based on an estimated power metric that comes closest tosatisfying the comparison, or on some other basis (e.g., based on adefault one of the permutations). When the respective estimated powermetrics are acquired at an intermediate point during the processing ofthe permutations at the separate transmit chain branches, processing ofthe permutations other than the selected one of the permutations may bediscontinued at the intermediate point. The discontinuation ofprocessing of non-selected permutations may save power.

In another example, the estimated power metric comparison module 760 maycompare the respective estimated power metrics to identify an optimalone of the estimated power metrics. When the respective estimated powermetrics are acquired at the ends of the separate transmit chainbranches, the permutation selection module 745 may select one of thepermutations for transmission from the unlicensed spectrum transmittermodule 734 based on the comparison. However, when the respectiveestimated power metrics are acquired at an intermediate point during theprocessing of the permutations at the separate transmit chain branches,the permutation selection module 745 may select one of the permutationsfor transmission only when the comparison made by the estimated powermetric comparison module 760 is conclusive (e.g., when the estimatedpower metric also satisfies a threshold). When it is determined that thecomparison is conclusive, processing of the permutations other than theselected one of the permutations may be discontinued at the intermediatepoint. The discontinuation of processing of non-selected permutationsmay save power. When it is determined that the comparison isinconclusive, it may be determined whether there exists an additionalintermediate point at which respected estimated power metrics may becompared, or respective estimated power metrics may be compared at theends of the separate transmit chain branches.

The permutation selection module 745 may in some cases select the one ofthe permutations for at least one of a slot, a subframe, or other blockof bits or modulation symbols of the stream. In these cases, therespective estimated power metrics of the permutations may includerespective estimated power metrics across all bits or modulation symbolsin the slot, subframe, or other block of bits or modulation symbols.

In some examples, the permutation communication module 750 may be usedto communicate, to a receiver, an indication of the permutation selectedby the permutation selection module 745. In some cases, the permutationcommunication module 750 may communicate the indication of the selectedpermutation using a reference signal modification module 765. Forexample, the permutation communication module 750 may use the referencesignal modification module 765 to modify a cyclic shift parameter of areference signal for the stream. The cyclic shift parameter may bemodified from an expected value such that the difference between themodified cyclic shift parameter and the expected value indicates theselected permutation. In some examples, the reference signal sequencefor which the cyclic shift parameter is modified may be or include aDM-RS.

FIG. 8 is a flow chart illustrating an example of a method 800 ofwireless communication, in accordance with various aspects of thepresent disclosure. For clarity, the method 800 is described below withreference to aspects of one or more of the UEs 115 or 215 described withreference to FIG. 1, 2A, or 2B, or one of the apparatuses 315, 615, or715 described with reference to FIG. 3, 6, or 7. In some examples, a UEsuch as one of the UEs 115 or 215 or an apparatus such as one of theapparatuses 315, 615, or 715 may execute one or more sets of codes tocontrol the functional elements of the UE or apparatus to perform thefunctions described below.

At block 805, a plurality of different permutations of a stream of bitsor modulation symbols may be generated. The stream of bits or modulationsymbols may in some cases be used for SC-FDMA-based transmissions on anLTE/LTE-A uplink channel in licensed or unlicensed spectrum. Theoperation(s) at block 805 may be performed by the wireless communicationmanagement module 320, 620, or 720 described with reference to FIG. 3,6, or 7, or the permutation generation module 635 or 735 described withreference to FIG. 6 or 7.

At block 810, each of the permutations generated at block 805 may beassociated with a separate transmit chain branch of a transmitter. Theoperation(s) at block 810 may be performed by the wireless communicationmanagement module 320, 620, or 720 described with reference to FIG. 3,6, or 7, or the permutation association module 640 or 740 described withreference to FIG. 6 or 7. The transmitter may in some cases be thetransmitter module 330, 430, 530, 630, or 730 described with referenceto FIG. 3, 4, 5, 6, or 7.

At block 815, one of the permutations may be selected for transmissionfrom the transmitter based on respective estimated power metrics (e.g.,PAPR or CM) of the permutations. The operation(s) at block 815 may beperformed by the wireless communication management module 320, 620, or720 described with reference to FIG. 3, 6, or 7, or the permutationselection module 645 or 745 described with reference to FIG. 6 or 7.

In some examples, the one of the permutations may be selected for atleast one of a slot, a subframe, or other block of bits or modulationsymbols of the stream. In these examples, the respective estimated powermetrics of the permutations may include respective estimated powermetrics across all bits or modulation symbols in the slot, subframe, orother block of bits or modulation symbols.

Thus, the method 800 may provide for wireless communication. It shouldbe noted that the method 800 is just one implementation and that theoperations of the method 800 may be rearranged or otherwise modifiedsuch that other implementations are possible.

FIG. 9 is a flow chart illustrating an example of a method 900 ofwireless communication, in accordance with various aspects of thepresent disclosure. For clarity, the method 900 is described below withreference to aspects of one or more of the UEs 115 or 215 described withreference to FIG. 1, 2A, or 2B, or one of the apparatuses 315, 615, or715 described with reference to FIG. 3, 6, or 7. In some examples, a UEsuch as one of the UEs 115 or 215 or an apparatus such as one of theapparatuses 315, 615, or 715 may execute one or more sets of codes tocontrol the functional elements of the UE or apparatus to perform thefunctions described below.

At block 905, a plurality of different permutations of a stream of bitsor modulation symbols may be generated, by multiplying the stream by amultiplier derived from at least one pseudo-random sequence. The streamof bits or modulation symbols may in some cases be used forSC-FDMA-based transmissions on an LTE/LTE-A uplink channel in licensedor unlicensed spectrum. The pseudo-random sequence may be known to boththe transmitter and to a receiver communicatively coupled with thetransmitter.

The operation(s) at block 905 may be performed by the wirelesscommunication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, or the permutation generation module 635or 735 described with reference to FIG. 6 or 7. The transmitter may insome cases be the transmitter module 330, 430, 530, 630, or 730described with reference to FIG. 3, 4, 5, 6, or 7.

At block 910, each of the permutations generated at block 905 may beassociated with a separate transmit chain branch of a transmitter. Theoperation(s) at block 910 may be performed by the wireless communicationmanagement module 320, 620, or 720 described with reference to FIG. 3,6, or 7, or the permutation association module 640 or 740 described withreference to FIG. 6 or 7.

At block 915, one of the permutations may be selected for transmissionfrom the transmitter based on respective estimated power metrics (e.g.,PAPR or CM) of the permutations. The operation(s) at block 915 may beperformed by the wireless communication management module 320, 620, or720 described with reference to FIG. 3, 6, or 7, or the permutationselection module 645 or 745 described with reference to FIG. 6 or 7.

In some examples, the one of the permutations may be selected for atleast one of a slot, a subframe, or other block of bits or modulationsymbols of the stream. In these examples, the respective estimated powermetrics of the permutations may include respective estimated powermetrics across all bits or modulation symbols in the slot, subframe, orother block of bits or modulation symbols.

At block 920, an indication of the selected permutation may becommunicated to a receiver. The selected permutation may becommunicated, in some examples, by modifying a cyclic shift parameter ofa reference signal sequence for the stream. The cyclic shift parametermay be modified from an expected value such that the difference betweenthe modified cyclic shift parameter and the expected value indicates theselected permutation. In some examples, the reference signal sequencefor which the cyclic shift parameter is modified may be or include aDM-RS. The operation(s) at block 920 may be performed by the wirelesscommunication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, or the permutation communication module750 or reference signal modification module 765 described with referenceto FIG. 7.

Thus, the method 900 may provide for wireless communication. It shouldbe noted that the method 900 is just one implementation and that theoperations of the method 900 may be rearranged or otherwise modifiedsuch that other implementations are possible.

FIG. 10 is a flow chart illustrating an example of a method 1000 ofwireless communication, in accordance with various aspects of thepresent disclosure. For clarity, the method 1000 is described below withreference to aspects of one or more of the UEs 115 or 215 described withreference to FIG. 1, 2A, or 2B, or one of the apparatuses 315, 615, or715 described with reference to FIG. 3, 6, or 7. In some examples, a UEsuch as one of the UEs 115 or 215 or an apparatus such as one of theapparatuses 315, 615, or 715 may execute one or more sets of codes tocontrol the functional elements of the UE or apparatus to perform thefunctions described below.

At block 1005, a plurality of different permutations of a stream of bitsor modulation symbols may be generated. The stream of bits or modulationsymbols may in some cases be used for SC-FDMA-based transmissions on anLTE/LTE-A uplink channel in licensed or unlicensed spectrum. Theoperation(s) at block 1005 may be performed by the wirelesscommunication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, or the permutation generation module 635or 735 described with reference to FIG. 6 or 7. The transmitter may insome cases be the transmitter module 330, 430, 530, 630, or 734described with reference to FIG. 3, 4, 5, 6, or 7.

At block 1010, each of the permutations generated at block 805 may beassociated with a separate transmit chain branch of a transmitter. Theoperation(s) at block 1010 may be performed by the wirelesscommunication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, or the permutation association module 640or 740 described with reference to FIG. 6 or 7.

At block 1015, the permutations may be processed at the separatetransmit chain branches of the transmitter. The operation(s) at block1015 may be performed by the transmitter module 330, 430, 630, or 730described with reference to FIG. 3, 4, 6, or 7, or the transmit chainbranches 435, 440, or 445 or 535, 540, or 545 described with referenceto FIG. 4 or 5.

At block 1020, respective estimated power metrics (e.g., PAPR or CM) ofthe permutations at ends of the separate transmit chain branches of thetransmitter may be compared to a threshold or to each other (e.g., toidentify one of the estimated power metrics that satisfies a thresholdor to identify an optimal one of the estimated power metrics). Theoperation(s) at block 1020 may be performed by the wirelesscommunication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, the permutation selection module 645 or745 described with reference to FIG. 6 or 7, or the estimated powermetric acquisition module 755 or estimated power metric comparisonmodule 760 described with reference to FIG. 7.

At block 1025, one of the permutations may be selected for transmissionfrom the transmitter. The one of the permutations may be selected basedon the comparison at block 1020. The operation(s) at block 1025 may beperformed by the wireless communication management module 320, 620, or720 described with reference to FIG. 3, 6, or 7, or the permutationselection module 645 or 745 described with reference to FIG. 6 or 7.

In some examples, the one of the permutations may be selected for atleast one of a slot, a subframe, or other block of bits or modulationsymbols of the stream. In these examples, the respective estimated powermetrics of the permutations may include respective estimated powermetrics across all bits or modulation symbols in the slot, subframe, orother block of bits or modulation symbols.

Thus, the method 1000 may provide for wireless communication. It shouldbe noted that the method 1000 is just one implementation and that theoperations of the method 1000 may be rearranged or otherwise modifiedsuch that other implementations are possible.

FIG. 11 is a flow chart illustrating an example of a method 1100 ofwireless communication, in accordance with various aspects of thepresent disclosure. For clarity, the method 1100 is described below withreference to aspects of one or more of the UEs 115 or 215 described withreference to FIG. 1, 2A, or 2B, or one of the apparatuses 315, 615, or715 described with reference to FIG. 3, 6, or 7. In some examples, a UEsuch as one of the UEs 115 or 215 or an apparatus such as one of theapparatuses 315, 615, or 715 may execute one or more sets of codes tocontrol the functional elements of the UE or apparatus to perform thefunctions described below.

At block 1105, a plurality of different permutations of a stream of bitsor modulation symbols may be generated. The stream of bits or modulationsymbols may in some cases be used for SC-FDMA-based transmissions on anLTE/LTE-A uplink channel in licensed or unlicensed spectrum. Theoperation(s) at block 1105 may be performed by the wirelesscommunication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, or the permutation generation module 635or 735 described with reference to FIG. 6 or 7. The transmitter may insome cases be the transmitter module 330, 430, 530, 630, or 730described with reference to FIG. 3, 4, 5, 6, or 7.

At block 1110, each of the permutations generated at block 805 may beassociated with a separate transmit chain branch of a transmitter. Theoperation(s) at block 1110 may be performed by the wirelesscommunication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, or the permutation association module 640or 740 described with reference to FIG. 6 or 7.

At block 1115, the permutations may be processed at the separatetransmit chain branches of the transmitter. The operation(s) at block1115 may be performed by the transmitter module 330, 430, 630, or 730described with reference to FIG. 3, 4, 6, or 7, or the transmit chainbranches 435, 440, or 445 or 535, 540, or 545 described with referenceto FIG. 4 or 5.

At block 1120, respective estimated power metrics (e.g., PAPR or CM) ofthe permutations at an intermediate point during the processing of thepermutations at the separate transmit chain branches of the transmittermay be compared to a threshold or to each other (e.g., to identify oneof the estimated power metrics that satisfies a threshold or to identifyan optimal one of the estimated power metrics). The operation(s) atblock 1120 may be performed by the wireless communication managementmodule 320, 620, or 720 described with reference to FIG. 3, 6, or 7, thepermutation selection module 645 or 745 described with reference to FIG.6 or 7, or the estimated power metric acquisition module 755 orestimated power metric comparison module 760 described with reference toFIG. 7.

At block 1125, it may be determined whether the comparison of therespective estimated power metrics of the permutations at theintermediate point is conclusive (e.g., when the estimated power metricalso satisfies a threshold). When it is determined that the comparisonis conclusive, one of the permutations may be selected at block 1130 fortransmission from the transmitter. The one of the permutations may beselected based on the comparison(s) at block 1120.

At block 1135, and in response to the determination that the comparisonat the intermediate point is conclusive, processing of the permutationsother than the selected one of the permutations may be discontinued atthe intermediate point. The discontinuation of processing ofnon-selected permutations may save power.

The operation(s) at block 1125, 1130, or 1135 may be performed by thewireless communication management module 320, 620, or 720 described withreference to FIG. 3, 6, or 7, or the permutation selection module 645 or745 described with reference to FIG. 6 or 7.

At block 1140, and when it is determined at block 1125 that thecomparison made at block 1120 is inconclusive, it may be determinedwhether there exists an additional intermediate point (e.g., anadditional intermediate point during the processing of the permutationsat the separate transmit chain branches of the transmitter) at whichrespective estimated power metrics of the permutations may be comparedto a threshold or to each other. When an additional intermediate pointexists, the flow of the method 1100 may return to block 1120, where therespective estimated power metrics of the permutations may be comparedto a threshold or to each other at the additional intermediate point.Otherwise, the method 1100 may continue to block 1145.

At block 1145, respective estimated power metrics of the permutations atends of the separate transmit chain branches of the transmitter may becompared to a threshold or each other (e.g., to identify one of theestimated power metrics that satisfies a threshold or to identify anoptimal one of the estimated power metrics). The operation(s) at block1145 may be performed by the wireless communication management module320, 620, or 720 described with reference to FIG. 3, 6, or 7, thepermutation selection module 645 or 745 described with reference to FIG.6 or 7, or the estimated power metric acquisition module 755 orestimated power metric comparison module 760 described with reference toFIG. 7.

At block 1150, one of the permutations may be selected for transmissionfrom the transmitter. The one of the permutations may be selected basedon the comparison(s) at block 1145. The operation(s) at block 1150 maybe performed by the wireless communication management module 320, 620,or 720 described with reference to FIG. 3, 6, or 7, or the permutationselection module 645 or 745 described with reference to FIG. 6 or 7.

In some examples, the one of the permutations selected at block 1130 orblock 1150 may be selected for at least one of a slot, a subframe, orother block of bits or modulation symbols of the stream. In theseexamples, the respective estimated power metrics of the permutations mayinclude respective estimated power metrics across all bits or modulationsymbols in the slot, subframe, or other block of bits or modulationsymbols.

Thus, the method 1100 may provide for wireless communication. It shouldbe noted that the method 1100 is just one implementation and that theoperations of the method 1100 may be rearranged or otherwise modifiedsuch that other implementations are possible.

In some cases, one or more aspects of the methods 800, 900, 1000, or1100 may be combined.

FIG. 12 illustrates an example 1200 of how allocated interlaces 1205 maybe partitioned for the purpose of performing joint interlace precodingusing joint precoding hardware 1210 configured for LTE/LTE-Acommunications, in accordance with various aspects of the presentdisclosure.

Current LTE/LTE-A standards mandate that resource blocks be allocated toUEs in multiples of 2, 3, or 5 RBs. As a result, currently availablejoint precoding hardware 1210 may only be able to precode (e.g., DFTprecode) groups of 2, 3, or 5 RBs. However, when making use of RBinterleaved uplink transmissions, situations may arise where a number ofinterlaces that is not a multiple of 2, 3, or 5 RBs (e.g., 7 interlaces)is allocated to a particular UE. Joint interlace precoding hardwarecapable of precoding 2, 3, 5, or some other number of RBs (e.g., 7 RBs)may therefore need to be designed. Alternately, when an unsupportednumber of interlaces is allocated to a UE, the allocated interlaces maybe partitioned into at least two subsets of interlaces 1215, 1220 (e.g.,a subset of interlaces 1215 including one interlace (e.g., RBs 1215-a,1215-b, and 1215-c), and a subset of interlaces 1220 including sixinterlaces (e.g., groups of RBs 1220-a, 1220-b, and 1220-c)), where asize of each subset of interlaces 1215, 1220 is supported by existingjoint precoding hardware 1210. Joint precoding may then be performed(e.g., for a stream of bits or modulation symbols) on each subset ofinterlaces 1215, 1220 separately. Thus, for example, an allocation ofseven interlaces, each having ten RBs, may be partitioned into a ratioof 10:60, 20:50, or 30:40 RBs. In some cases, the size of each subset ofinterlaces may be selected based on a power metric associated with acombination of the selected sizes. For example, a partitioning thatoptimizes a power metric (e.g., reduces PAPR or CM) for the combinationof the selected sizes may be selected.

In some examples, each of the at least two subsets of interlaces 1215,1220 may be separately processed by the same joint precoding hardware1210, in which case blocks 1210-a and 1210-b may represent the samejoint precoding hardware 1210 at different points in time. In otherexamples, each of the at least two subsets of interlaces 1215, 1220 maybe separately processed by different joint precoding hardware 1210, inwhich case the blocks 1210-a and 1210-b may represent the differentjoint precoding hardware. An output of the joint interlace precoding maybe provided to a downstream processing module, such as an IDFT module.

FIG. 13 shows a block diagram 1300 of an apparatus 1315 for use inwireless communication, in accordance with various aspects of thepresent disclosure. In some examples, the apparatus 1315 may be anexample of one or more aspects of one of the UEs 115 or 215 describedwith reference to FIG. 1, 2A, or 2B, or the apparatus 315, 615, or 715described with reference to FIG. 3, 6, or 7. The apparatus 1315 may alsobe a processor. The apparatus 1315 may include a receiver module 1310, awireless communication management module 1320, or a transmitter module1330. Each of these components may be in communication with each other.

The components of the apparatus 1315 may, individually or collectively,be implemented using one or more ASICs adapted to perform some or all ofthe applicable functions in hardware. Alternatively, the functions maybe performed by one or more other processing units (or cores), on one ormore integrated circuits. In other examples, other types of integratedcircuits may be used (e.g., Structured/Platform ASICs, FPGAs, and otherSemi-Custom ICs), which may be programmed in any manner known in theart. The functions of each unit may also be implemented, in whole or inpart, with instructions embodied in a memory, formatted to be executedby one or more general or application-specific processors.

In some examples, the receiver module 1310 may be or include a radiofrequency (RF) receiver, such as an RF receiver operable to receivetransmissions in a first spectrum (e.g., an LTE/LTE-A licensed spectrum)or a second spectrum (e.g., an LTE/LTE-A unlicensed spectrum, whichunlicensed spectrum may be shared with one or more apparatuses operatingunder the same or different transmission protocols, and which unlicensedspectrum may include WiFi spectrum). The RF receiver may includeseparate receivers for the first spectrum and the second spectrum. Theseparate receivers may in some cases take the form of a licensedspectrum receiver module 1312 for communicating over the first spectrum,and an unlicensed spectrum receiver module 1314 for communicating overthe second spectrum. The receiver module 1310, including the licensedspectrum receiver module 1312 or the unlicensed spectrum receiver module1314, may be used to receive various types of data or control signals(i.e., transmissions) over one or more communication links of a wirelesscommunications system including the first and second spectrums, such asone or more communication links of the wireless communications system100, 200, or 250 described with reference to FIG. 1, 2A, or 2B.

In some examples, the transmitter module 1330 may be or include an RFtransmitter, such as an RF transmitter operable to transmit in the firstspectrum or the second spectrum. The RF transmitter may include separatetransmitters for the first spectrum and the second spectrum. Theseparate transmitters may in some cases take the form of a licensedspectrum transmitter module 1332 for communicating over the firstspectrum, and an unlicensed spectrum transmitter module 1334 forcommunicating over the second spectrum. The transmitter module 1330,including the licensed spectrum transmitter module 1332 or theunlicensed spectrum transmitter module 1334, may be used to transmitvarious types of data or control signals (i.e., transmissions) over oneor more communication links of the wireless communications systemincluding the first spectrum and the second spectrum. In some cases, theunlicensed spectrum transmitter module 1334 may include joint interlaceprecoding hardware 1336, such as the joint precoding hardware 1210described with reference to FIG. 12.

In some examples, the wireless communication management module 1320 maybe an example of one or more aspects of the wireless communicationmanagement module 320, 620, or 720 described with reference to FIG. 3,6, or 7 and may include an allocated interlace reception module 1335 oran allocated interlace partitioning module 1340. Each of thesecomponents may be in communication with each other.

In some examples, the allocated interlace reception module 1335 may beused to receive a number of allocated interlaces for an uplinktransmission over a shared spectrum (e.g., an unlicensed spectrum inwhich LTE/LTE-A communications may be transmitted using the unlicensedspectrum transmitter module 1334). Each interlace may include aplurality of non-contiguous RBs of the shared spectrum. In some cases,the number of allocated interlaces may be unsupported by the jointinterlace precoding hardware 1336 of the unlicensed spectrum transmittermodule 1334. In some cases, the number of allocated interlaces may beseven.

In some examples, the allocated interlace partitioning module 1340 maybe used to partition the allocated interlaces received by the allocatedinterlace reception module 1335 into at least two subsets of interlaces,such that a size of each subset of interlaces is supported by the jointinterlace precoding hardware 1336 of the unlicensed spectrum transmittermodule 1334. The size of each subset of interlaces may in some cases beselected based on a power metric (e.g., PAPR or CM) associated with acombination of the selected sizes for the apparatus 1315. For example,the size of each subset of interlaces may be selected to reduce a PAPRor CM associated with the combination of the selected sizes. In the casewhere seven allocated interlaces are received by the allocated interlacereception module 1335, the allocated interlace partitioning module 1340may partition the allocated interlaces into a first set of one interlaceand a second set of six interlaces.

In some examples, the joint interlace precoding hardware 1336 may beused to perform joint interlace precoding separately on each subset ofinterlaces defined by the allocated interlace partitioning module 1340.The precoded subsets of interlaces may then be transmitted over theshared spectrum, to a base station, by the unlicensed spectrumtransmitter module 1334.

FIG. 14 is a flow chart illustrating an example of a method 1400 ofwireless communication, in accordance with various aspects of thepresent disclosure. For clarity, the method 1400 is described below withreference to aspects of one or more of the UEs 115 or 215 described withreference to FIG. 1, 2A, or 2B, or one of the apparatuses 315 or 1315described with reference to FIG. 3 or 13. In some examples, a UE such asone of the UEs 115 or 215 or an apparatus such as one of the apparatuses315 or 1315 may execute one or more sets of codes to control thefunctional elements of the UE or apparatus to perform the functionsdescribed below.

At block 1405, a number of allocated interlaces for an uplinktransmission over a shared spectrum (e.g., an unlicensed spectrum inwhich LTE/LTE-A communications may be transmitted using the unlicensedspectrum transmitter module 1334) may be received at a UE. Eachinterlace may include a plurality of non-contiguous RBs of the sharedspectrum. In some cases, the number of allocated interlaces may beunsupported by joint interlace precoding hardware of the UE. In somecases, the number of allocated interlaces may be seven. The operation(s)at block 1405 may be performed by the wireless communication managementmodule 320 or 1320 described with reference to FIG. 3 or 13, or theallocated interlace reception module 1335 described with reference toFIG. 13.

At block 1410, the allocated interlaces may be partitioned into at leasttwo subsets of interlaces, such that a size of each subset of interlacesis supported by the joint interlace precoding hardware of the UE. Thesize of each subset of interlaces may in some cases be selected based ona power metric (e.g., PAPR or CM) associated with a combination of theselected sizes for the UE. For example, the size of each subset ofinterlaces may be selected to reduce a PAPR or CM associated with thecombination of the selected sizes. In the case where seven allocatedinterlaces are received at the UE, the allocated interlaces may bepartitioned into a first set of one interlace and a second set of sixinterlaces. The operation(s) at block 1410 may be performed by thewireless communication management module 320 or 1320 described withreference to FIG. 3 or 13, or the allocated interlace partitioningmodule 1340 described with reference to FIG. 13.

At block 1415, joint interlace precoding may be performed separately oneach subset of interlaces at the UE. The operation(s) at block 1415 maybe performed by the wireless communication management module 320 or 1320described with reference to FIG. 3 or 13, or the joint precodinghardware 1210 or 1336 described with reference to FIG. 12 or 13.

At block 1420, the precoded subsets of interlaces may be transmittedover the shared spectrum to a base station.

Thus, the method 1400 may provide for wireless communication. It shouldbe noted that the method 1400 is just one implementation and that theoperations of the method 1400 may be rearranged or otherwise modifiedsuch that other implementations are possible.

FIGS. 15 & 16 illustrate examples of how a reference signal may begenerated for each resource block of a number of allocated interlacesfor an uplink transmission over a shared spectrum. More specifically,FIG. 15 illustrates an example 1500 of how a reference signal (e.g., ademodulation reference signal (DM-RS)) may be generated for eachresource block of a number of allocated interlaces for an uplinktransmission over a shared spectrum, in accordance with various aspectsof the present disclosure. By way of example, FIG. 15 illustrates aportion of ten interlaces, of which three interlaces 1505, 1510, and1515 out of the ten interlaces are allocated to a particular UE. Each ofthe blocks 1505-a, 1510-a, 1515-a, 1505-b, 1510-b, 1515-b, 1505-c,1510-c, and 1515-c may represent a single RB including twelve frequencysubcarriers, and each interlace 1505, 1510, and 1515 may include tennon-contiguous RBs (though only three RBs of each interlace are shown inFIG. 15). According to the example 1500, a reference signal sequence maybe generated based solely on the allocated interlaces 1505, 1510, and1515. Thus, for example, a reference signal sequence having 360reference signal symbols may be generated (e.g., 10 RB/interlace×3allocated interlaces×12 frequency subcarriers/RB). The reference signalsymbols from the reference signal sequence may then be mapped to the RBsof the allocated interlaces according to frequency. In this manner, areference signal (e.g., x1, x2, x3, x4, . . . ) generated for each RB(1505-a, 1510-a, 1515-a, 1505-b, . . . ) of the allocated interlaces mayinclude the reference signal symbols mapped to that resource block.

FIG. 16 illustrates another example 1600 of how a reference signal(e.g., a DM-RS) may be generated for each RB of a number of allocatedinterlaces for an uplink transmission over a shared spectrum, inaccordance with various aspects of the present disclosure. By way ofexample, FIG. 16 illustrates a portion of ten interlaces, of which threeinterlaces 1605, 1610, and 1615 out of the ten interlaces are allocatedto a particular UE. Each of the blocks 1605-a, 1610-a, 1615-a, 1605-b,1610-b, 1615-b, 1605-c, 1610-c, and 1615-c may represent a single RBincluding twelve frequency subcarriers, and each interlace 1605, 1610,and 1615 may include ten non-contiguous RBs (though only three RBs ofeach interlace are shown in FIG. 16). According to the example 1600, areference signal sequence may be generated based on the allocatedinterlaces 1605, 1610, and 1615 as well as the unallocated interlaces1620, 1625, 1630, 1635, 1640, 1645, and 1650. Thus, for example, areference signal sequence having 1200 reference signal symbols may begenerated (e.g., 10 RB/interlace×10 interlaces×12 frequencysubcarriers/RB). The reference signal symbols from the reference signalsequence may then be mapped to the RBs of both the allocated interlacesand the unallocated interlaces according to frequency. In this manner,the reference signal sequence may be punctured when mapping referencesignal symbols to the allocated interlaces 1605, 1610, and 1615. Areference signal (e.g., x₁, x₂, x₃, x₁₁, . . . ) generated for eachrespective RB (1605-a, 1610-a, 1615-a, 1605-b, . . . ) of the allocatedinterlaces may include the reference signal symbols mapped to thatresource block.

In some cases, a number of computer generated sequences (CGS) aregenerated and may be used as reference signals (e.g., DM-RS). The numberof CGSs may be predetermined, such as a factor, in some cases ten, timesthe number of allocated interlaces or based on implementation factors.For example, a UE with three allocated interlaces may be associated withthirty CGSs. The CGSs may be optimized for low circular crosscorrelation, and in some cases are used for physical uplink controlchannel (PUCCH) estimation. In some cases, the CGSs are of lengthtwelve, such as to correspond with twelve frequency subcarriers of eachRB, though the CGSs may be of any length appropriate for the specificimplementation. In some examples, the CGSs are allocated, such asrandomly or systematically, to RBs of the allocated interlaces. In thecurrent example, the UE with three allocated interlaces may allocate oneof 30 length 12 sequences to each active RB in each interlace. It shouldbe noted that there is a chance that UEs of different neighboring basestations pick the same CGS in a given RB, which may result in poorchannel estimates at the base station. In order to avoid this, more CGSsmay be generated. In some cases, a random cyclic shift may be added ontop of each CGS to reduce interference in case of a collision.

In some examples, reference signals (e.g., DM-RS) may be a combinationof CGSs and Zadoff-Chu (ZC) sequences. For example, a reference signalsequence may consist of an inner CGS and an outer ZC sequence. The innersequence may be a randomly chosen CGS and may be common to all the RBsin an interlace. The outer sequence may be the length of the number ofRBs in an interlace, such as ten. At times, the outer sequence isgenerated with a root that is relatively prime to the length, such asthree, seven, or nine if the length is ten. Interlaces allocated to thesame UE may contain the same outer ZC sequence. The outer ZC sequencemay differ between UEs. The reference signal for an interlace may be aKronecker product of the outer ZC sequence and the inner CGS. In somecases, this reference signal has good circular auto-correlation.

FIG. 17 shows a block diagram 1700 of an apparatus 1715 for use inwireless communication, in accordance with various aspects of thepresent disclosure. In some examples, the apparatus 1715 may be anexample of one or more aspects of one of the UEs 115 or 215 describedwith reference to FIG. 1, 2A, or 2B, or the apparatus 315, 615, 715, or1315 described with reference to FIG. 3, 6, 7, or 13. The apparatus 1715may also be a processor. The apparatus 1715 may include a receivermodule 1710, a wireless communication management module 1720, or atransmitter module 1730. Each of these components may be incommunication with each other.

The components of the apparatus 1715 may, individually or collectively,be implemented using one or more ASICs adapted to perform some or all ofthe applicable functions in hardware. Alternatively, the functions maybe performed by one or more other processing units (or cores), on one ormore integrated circuits. In other examples, other types of integratedcircuits may be used (e.g., Structured/Platform ASICs, FPGAs, and otherSemi-Custom ICs), which may be programmed in any manner known in theart. The functions of each unit may also be implemented, in whole or inpart, with instructions embodied in a memory, formatted to be executedby one or more general or application-specific processors.

In some examples, the receiver module 1710 may be or include a radiofrequency (RF) receiver, such as an RF receiver operable to receivetransmissions in a first spectrum (e.g., an LTE/LTE-A licensed spectrum)or a second spectrum (e.g., an LTE/LTE-A unlicensed spectrum, whichunlicensed spectrum may be shared with one or more apparatuses operatingunder the same or different transmission protocols, and which unlicensedspectrum may include WiFi spectrum). The RF receiver may includeseparate receivers for the first spectrum and the second spectrum. Theseparate receivers may in some cases take the form of a licensedspectrum receiver module 1712 for communicating over the first spectrum,and an unlicensed spectrum receiver module 1714 for communicating overthe second spectrum. The receiver module 1710, including the licensedspectrum receiver module 1712 or the unlicensed spectrum receiver module1714, may be used to receive various types of data or control signals(i.e., transmissions) over one or more communication links of a wirelesscommunications system including the first and second spectrums, such asone or more communication links of the wireless communications system100, 200, or 250 described with reference to FIG. 1, 2A, or 2B.

In some examples, the transmitter module 1730 may be or include an RFtransmitter, such as an RF transmitter operable to transmit in the firstspectrum or the second spectrum. The RF transmitter may include separatetransmitters for the first spectrum and the second spectrum. Theseparate transmitters may in some cases take the form of a licensedspectrum transmitter module 1732 for communicating over the firstspectrum, and an unlicensed spectrum transmitter module 1734 forcommunicating over the second spectrum. The transmitter module 1730,including the licensed spectrum transmitter module 1732 or theunlicensed spectrum transmitter module 1734, may be used to transmitvarious types of data or control signals (i.e., transmissions) over oneor more communication links of the wireless communications systemincluding the first spectrum and the second spectrum.

In some examples, the wireless communication management module 1720 maybe an example of one or more aspects of the wireless communicationmanagement module 320, 620, 720, or 1320 described with reference toFIG. 3, 6, 7, or 13 and may include an allocated interlace receptionmodule 1735 or a reference signal generation module 1740. Each of thesecomponents may be in communication with each other.

In some examples, the allocated interlace reception module 1735 may beused to receive a number of allocated interlaces for an uplinktransmission over a shared spectrum (e.g., an unlicensed spectrum inwhich LTE/LTE-A communications may be transmitted). Each interlace mayinclude a plurality of non-contiguous RBs of the shared spectrum.

In some examples, the reference signal generation module 1740 may beused to generate a reference signal (e.g., a DM-RS) for each RB of theallocated interlaces according to a reference signal sequence based onan ordering of the RBs for the allocated interlaces within the sharedspectrum.

In some cases, the reference signal generation module 1740 may generatethe reference signals for the RBs by mapping reference signal symbolsfrom the reference signal sequence to the RBs of the allocatedinterlaces within the shared spectrum according to frequency, such thatthe reference signal generated for each RB of the allocated interlacesincludes the reference signal symbols mapped to that RB, as described,for example, with reference to FIG. 15.

In other cases, the shared spectrum may include a plurality of RBsassociated with at least one unallocated interlace, and the referencesignal generation module 1740 may generate the reference signals for theRBs by mapping reference signal symbols from the reference signalsequence to the RBs of the allocated interlaces and the at least oneunallocated interlace according to frequency, and by puncturing thereference signal sequence to determine a subset of reference signalsymbols mapped to the RBs of the allocated interlaces, such that thereference signal generated for each RB of the allocated interlacesincludes the reference signal symbol mapped to that RB, as described,for example, with reference to FIG. 16.

FIG. 18 is a flow chart illustrating an example of a method 1800 ofwireless communication, in accordance with various aspects of thepresent disclosure. For clarity, the method 1800 is described below withreference to aspects of one or more of the UEs 115 or 215 described withreference to FIG. 1, 2A, or 2B, or one of the apparatuses 315 or 1715described with reference to FIG. 3 or 17. In some examples, a UE such asone of the UEs 115 or 215 or an apparatus such as one of the apparatuses315 or 1715 may execute one or more sets of codes to control thefunctional elements of the UE or apparatus to perform the functionsdescribed below.

At block 1805, a number of allocated interlaces for an uplinktransmission over a shared spectrum (e.g., an unlicensed spectrum inwhich LTE/LTE-A communications may be transmitted) may be received at aUE. Each allocated interlace may include a plurality of non-contiguousRBs of the shared spectrum. The operation(s) at block 1805 may beperformed by the wireless communication management module 320 or 1720described with reference to FIG. 3 or 17, or the allocated interlacereception module 1735 described with reference to FIG. 17.

At block 1810, a reference signal (e.g., a DM-RS) may be generated foreach RB of the allocated interlaces according to a reference signalsequence based on an ordering of the RBs for the allocated interlaceswithin the shared spectrum. The operation(s) at block 1810 may beperformed by the wireless communication management module 320 or 1720described with reference to FIG. 3 or 17, or the reference signalgeneration module 1740 described with reference to FIG. 17.

In some examples, generating the reference signals for the RBs mayinclude mapping reference signal symbols from the reference signalsequence to the RBs of the allocated interlaces within the sharedspectrum according to frequency, such that the reference signalgenerated for each RB of the allocated interlaces includes the referencesignal symbols mapped to that RB, as described, for example, withreference to FIG. 15.

In other examples, the shared spectrum may include a plurality of RBsassociated with at least one unallocated interlace, and generating thereference signals for the RBs may include mapping reference signalsymbols from the reference signal sequence to the RBs of the allocatedinterlaces and the at least one unallocated interlace according tofrequency, and puncturing the reference signal sequence to determine asubset of reference signal symbols mapped to the RBs of the allocatedinterlaces, such that the reference signal generated for each RB of theallocated interlaces includes the reference signal symbol mapped to thatRB, as described, for example, with reference to FIG. 16.

Thus, the method 1800 may provide for wireless communication. It shouldbe noted that the method 1800 is just one implementation and that theoperations of the method 1800 may be rearranged or otherwise modifiedsuch that other implementations are possible.

FIG. 19 illustrates an example 1900 of how a plurality of resourceelements positions (e.g., resource element positions 1910, 1915, etc.)in a subframe 1905 may be mapped to a plurality of DM-RS transmissions(e.g., DM-RS transmissions 1920, 1925, etc.) over a shared spectrum, inaccordance with various aspects of the present disclosure. Morespecifically, FIG. 19 illustrates how at least one of the DM-RStransmissions may be multiplexed with at least one data transmissionduring at least one FDMA symbol of the subframe 1905. Even morespecifically, FIG. 19 illustrates how two DM-RS transmissions 1920 and1925 may be 1) distributed in a resource element group includingmultiple (e.g., two) contiguous ones of the resource element positions,and 2) multiplexed with data transmissions in resource element positionssuch as resource element positions 1930 and 1935. By way of example, theresource element group includes resource element positions 1910 and 1915belonging to different frequency subcarriers. Other DM-RS transmissionsmay be distributed in other resource element groups. Alternately, one ormore (and even all) of the DM-RS transmissions may be transmitted apartfrom any resource element group. As shown, the DM-RS transmissions maybe distributed across most all of the FDMA symbols of the subframe 1905(e.g., all but two FDMA symbols).

In some cases, a DM-RS generated as described with reference to FIG. 15may be mapped to a plurality of resource element positions as describedwith reference to FIG. 19. In other cases, a DM-RS generated asdescribed with reference to FIG. 16 may be mapped to a plurality ofresource element positions as described with reference to FIG. 19.

When a plurality of resource element positions in a subframe are mappedto a plurality of DM-RS transmissions as described with reference toFIG. 19, PAPR may not be a strong function of the choice of DM-RSsequence. In addition, the mapping described with reference to FIG. 19may be a better mapping for estimating bursty interference, as it spansmost of the FDMA symbols of a subframe. However, PAPR may be slightlyhigher (statistically) than when DM-RS transmissions are not multiplexedwith data transmissions (e.g., because precoded symbols are mixed withDM-RS transmissions).

FIG. 20 shows a block diagram 2000 of an apparatus 2015 for use inwireless communication, in accordance with various aspects of thepresent disclosure. In some examples, the apparatus 2015 may be anexample of one or more aspects of one of the UEs 115 or 215 describedwith reference to FIG. 1, 2A, or 2B, or the apparatus 315, 615, 715,1315, or 1715 described with reference to FIG. 3, 6, 7, 13, or 17. Theapparatus 2015 may also be a processor. The apparatus 2015 may include areceiver module 2010, a wireless communication management module 2020,or a transmitter module 2030. Each of these components may be incommunication with each other.

The components of the apparatus 2015 may, individually or collectively,be implemented using one or more ASICs adapted to perform some or all ofthe applicable functions in hardware. Alternatively, the functions maybe performed by one or more other processing units (or cores), on one ormore integrated circuits. In other examples, other types of integratedcircuits may be used (e.g., Structured/Platform ASICs, FPGAs, and otherSemi-Custom ICs), which may be programmed in any manner known in theart. The functions of each unit may also be implemented, in whole or inpart, with instructions embodied in a memory, formatted to be executedby one or more general or application-specific processors.

In some examples, the receiver module 2010 may be or include a radiofrequency (RF) receiver, such as an RF receiver operable to receivetransmissions in a first spectrum (e.g., an LTE/LTE-A licensed spectrum)or a second spectrum (e.g., an LTE/LTE-A unlicensed spectrum, whichunlicensed spectrum may be shared with one or more apparatuses operatingunder the same or different transmission protocols, and which unlicensedspectrum may include WiFi spectrum). The RF receiver may includeseparate receivers for the first spectrum and the second spectrum. Theseparate receivers may in some cases take the form of a licensedspectrum receiver module 2012 for communicating over the first spectrum,and an unlicensed spectrum receiver module 2014 for communicating overthe second spectrum. The receiver module 2010, including the licensedspectrum receiver module 2012 or the unlicensed spectrum receiver module2014, may be used to receive various types of data or control signals(i.e., transmissions) over one or more communication links of a wirelesscommunications system including the first and second spectrums, such asone or more communication links of the wireless communications system100, 200, or 250 described with reference to FIG. 1, 2A, or 2B.

In some examples, the transmitter module 2030 may be or include an RFtransmitter, such as an RF transmitter operable to transmit in the firstspectrum or the second spectrum. The RF transmitter may include separatetransmitters for the first spectrum and the second spectrum. Theseparate transmitters may in some cases take the form of a licensedspectrum transmitter module 2032 for communicating over the firstspectrum, and an unlicensed spectrum transmitter module 2034 forcommunicating over the second spectrum. The transmitter module 2030,including the licensed spectrum transmitter module 2032 or theunlicensed spectrum transmitter module 2034, may be used to transmitvarious types of data or control signals (i.e., transmissions) over oneor more communication links of the wireless communications systemincluding the first spectrum and the second spectrum.

In some examples, the wireless communication management module 2020 maybe an example of one or more aspects of the wireless communicationmanagement module 320, 620, 720, 1320, or 2020 described with referenceto FIG. 3, 6, 7, 13, or 20 and may include a resource element mappingmodule 2035.

In some examples, the resource element mapping module 2035 may be usedto map a plurality of resource element positions in a subframe (e.g., anuplink subframe) to a plurality of DM-RS transmissions over the secondspectrum, where at least one of the DM-RS transmissions may bemultiplexed with at least one data transmission during at least one FDMAsymbol (e.g., an SC-FDMA symbol) of the subframe, as described, forexample, with reference to FIG. 19.

In some cases, the resource element mapping module 2035 may distributethe plurality of DM-RS transmissions across a plurality of FDMA symbols(e.g., all but two of the FDMA symbols) of the subframe.

In some cases, the resource element mapping module 2035 may distributethe plurality of DM-RS transmissions in a plurality of resource elementgroups, with each resource element group including multiple contiguousones of the resource element positions (e.g., multiple contiguousresource elements in the time domain or the frequency domain).

In some cases, the resource element mapping module 2035 may map at leastone DM-RS transmission to each of a plurality of frequency subcarriersof the subframe.

The unlicensed spectrum transmitter module 2034 may be used to transmitthe DM-RS transmissions over the second spectrum according to the mappedresource element positions in the subframe.

FIG. 21 is a flow chart illustrating an example of a method 2100 ofwireless communication, in accordance with various aspects of thepresent disclosure. For clarity, the method 2100 is described below withreference to aspects of one or more of the UEs 115 or 215 described withreference to FIG. 1, 2A, or 2B, or one of the apparatuses 315 or 2015described with reference to FIG. 3 or 20. In some examples, a UE such asone of the UEs 115 or 215 or an apparatus such as one of the apparatuses315 or 2015 may execute one or more sets of codes to control thefunctional elements of the UE or apparatus to perform the functionsdescribed below.

At block 2105, a plurality of resource element positions in a subframe(e.g., an uplink subframe) may be mapped to a plurality of DM-RStransmissions over a shared spectrum (e.g., an unlicensed spectrum inwhich LTE/LTE-A communications may be transmitted), where at least oneof the DM-RS transmissions may be multiplexed with at least one datatransmission during at least one FDMA symbol (e.g., an SC-FDMA symbol)of the subframe, as described, for example, with reference to FIG. 19.The operation(s) at block 2105 may be performed by the wirelesscommunication management module 320 or 2020 described with reference toFIG. 3 or 20, or the resource element mapping module 2035 described withreference to FIG. 20.

In some cases, the plurality of DM-RS transmissions may be distributedacross a plurality of FDMA symbols (e.g., all but two of the FDMAsymbols) of the subframe.

In some cases, the plurality of DM-RS transmissions may be distributedin a plurality of resource element groups, with each resource elementgroup including multiple contiguous ones of the resource elementpositions (e.g., multiple contiguous resource elements in the timedomain or the frequency domain).

In some cases, at least one DM-RS transmission may be mapped to each ofa plurality of frequency subcarriers of the subframe.

At block 2110, the DM-RS transmissions may be transmitted over theunlicensed spectrum according to the mapped resource element positionsin the subframe. The operation(s) at block 2110 may be performed by thetransmitter module 330 or 2030 described with reference to FIG. 3 or 20,or the unlicensed spectrum transmitter module 2034 described withreference to FIG. 20.

Thus, the method 2100 may provide for wireless communication. It shouldbe noted that the method 2100 is just one implementation and that theoperations of the method 2100 may be rearranged or otherwise modifiedsuch that other implementations are possible.

In some examples, one or more aspects of the methods 800, 900, 1000,1100, 1400, 1800, or 2100 may be combined.

The detailed description set forth above in connection with the appendeddrawings describes examples and does not represent the only examplesthat may be implemented or that are within the scope of the claims. Theterms “example” and “exemplary,” when used in this description, mean“serving as an example, instance, or illustration,” and not “preferred”or “advantageous over other examples.” The detailed description includesspecific details for the purpose of providing an understanding of thedescribed techniques. These techniques, however, may be practicedwithout these specific details. In some instances, well-known structuresand apparatuses are shown in block diagram form in order to avoidobscuring the concepts of the described examples.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a digital signal processor (DSP), an ASIC, anFPGA or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, or any combination thereof designedto perform the functions described herein. A general-purpose processormay be a microprocessor, but in the alternative, the processor may beany conventional processor, controller, microcontroller, or statemachine. A processor may also be implemented as a combination ofcomputing devices, e.g., a combination of a DSP and a microprocessor,multiple microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope and spirit of the disclosure and appended claims. For example,due to the nature of software, functions described above can beimplemented using software executed by a processor, hardware, firmware,hardwiring, or combinations of any of these. Features implementingfunctions may also be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations. Also, as used herein, including in theclaims, “or” as used in a list of items prefaced by “at least one of”indicates a disjunctive list such that, for example, a list of “at leastone of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., Aand B and C).

Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation,computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. By way of furtherexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such asinfrared, radio, and microwave, then the coaxial cable, fiber opticcable, twisted pair, DSL, or wireless technologies such as infrared,radio, and microwave are included in the definition of medium. Disk anddisc, as used herein, include compact disc (CD), laser disc, opticaldisc, digital versatile disc (DVD), floppy disk and Blu-ray disc wheredisks usually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above are also includedwithin the scope of computer-readable media.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Throughout this disclosure the term “example” or“exemplary” indicates an example or instance and does not imply orrequire any preference for the noted example. Thus, the disclosure isnot to be limited to the examples and designs described herein but is tobe accorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method of wireless communication, comprising:receiving at a user equipment (UE) a number of interlaces allocated tothe UE on a per-UE basis for an uplink transmission over a contentionbased shared spectrum, wherein each allocated interlace comprises aplurality of resource blocks of the contention based shared spectrum ina carrier of a frequency domain, wherein each resource block of theplurality of resource blocks of each interlace is non-contiguous with aremainder of the plurality of resource blocks of that interlace; andgenerating reference signals for resource blocks of the allocatedinterlaces according to a reference signal sequence based at least inpart on an ordering of the resource blocks of the allocated interlaceswithin the contention based shared spectrum in the carrier of thefrequency domain, wherein the ordering of the resource blocks comprisesat least a lower-ordered resource block and a higher-ordered resourceblock, wherein a single reference signal is generated for at least oneinterlace of the allocated interlaces, the at least one interlacecomprising a plurality of the resource blocks that are eachnon-contiguous, wherein the single reference signal is mapped to theplurality of the resource blocks, and wherein the mapping comprisesmapping the lower-ordered resource block before mapping thehigher-ordered resource block.
 2. The method of claim 1, whereingenerating the reference signals comprises: mapping reference signalsymbols from the reference signal sequence to the resource blocks of theallocated interlaces within the contention based shared spectrumaccording to frequency.
 3. The method of claim 1, wherein the contentionbased shared spectrum comprises a plurality of resource blocksassociated with at least one unallocated interlace, wherein generatingthe reference signals comprises: mapping reference signal symbols fromthe reference signal sequence to the resource blocks of the allocatedinterlaces and the at least one unallocated interlace according tofrequency; and puncturing the reference signal sequence to determine asubset of reference signal symbols mapped to the resource blocks of theallocated interlaces; wherein a separate reference signal is generatedfor each of the resource blocks of the allocated interlaces based atleast in part on the reference signal symbols mapped to that resourceblock.
 4. The method of claim 1, wherein generating the referencesignals comprises: generating a number of computer generated sequences;and mapping one of the computer generated sequences to one of theresource blocks of the allocated interlaces within the contention basedshared spectrum.
 5. The method of claim 4, wherein a length of thecomputer generated sequences is based at least in part on a number offrequency subcarriers for the resource blocks.
 6. The method of claim 4,wherein the number of computer generated sequences is based at least inpart on the number of allocated interlaces.
 7. The method of claim 4,further comprising: shifting at least one of the computer generatedsequences based at least in part on a random cyclic shift.
 8. The methodof claim 4, wherein mapping one of the computer generated sequences toone of the resource blocks comprises: generating an outer sequence;determining a number of combined sequences, wherein the combinedsequences are based at least in part on at least one of the computergenerated sequences and the outer sequence; and mapping one of thecombined sequences to one of the resource blocks of the allocatedinterlaces within the contention based shared spectrum.
 9. The method ofclaim 1, further comprising: transmitting the uplink transmission overthe contention based shared spectrum, wherein the uplink transmissioncomprises at least one of the allocated interlaces.
 10. The method ofclaim 1, wherein a separate reference signal is generated for each ofthe resource blocks of the allocated interlaces based at least in parton the reference signal symbols mapped to that resource block.
 11. Anapparatus for wireless communication, comprising: a processor; andmemory coupled to the processor, wherein the processor is configured to:receive at a user equipment (UE) a number of interlaces allocated to theUE on a per-UE basis for an uplink transmission over a contention basedshared spectrum, wherein each allocated interlace comprises a pluralityof resource blocks of the contention based shared spectrum in a carrierof a frequency domain, wherein each resource block of the plurality ofresource blocks of each interlace is non-contiguous with a remainder ofthe plurality of resource blocks of that interlace; and generatereference signals for resource blocks of the allocated interlacesaccording to a reference signal sequence based at least in part on anordering of the resource blocks for the allocated interlaces within thecontention based shared spectrum in the carrier of the frequency domain,wherein the ordering of the resource blocks comprises at least alower-ordered resource block and a higher-ordered resource block,wherein a single reference signal is generated for at least oneinterlace of the allocated interlaces, the at least one interlacecomprising a plurality of the resource blocks that are eachnon-contiguous, and wherein the single reference signal is mapped to theplurality of the resource blocks, and wherein the mapping comprisesmapping the lower-ordered resource block before mapping thehigher-ordered resource block.
 12. The apparatus of claim 11, whereinthe processor is further configured to: map reference signal symbolsfrom the reference signal sequence to the resource blocks of theallocated interlaces within the contention based shared spectrumaccording to frequency; wherein a separate reference signal is generatedfor each of the resource blocks of the allocated interlaces based atleast in part on the reference signal symbols mapped to that resourceblock.
 13. The apparatus of claim 11, wherein the contention basedshared spectrum comprises a plurality of resource blocks associated withat least one unallocated interlace, and wherein the processor isconfigured to generate the reference signals by: mapping referencesignal symbols from the reference signal sequence to the resource blocksof the allocated interlaces and the at least one unallocated interlaceaccording to frequency; and puncturing the reference signal sequence todetermine a subset of reference signal symbols mapped to the resourceblocks of the allocated interlaces; wherein a separate reference signalis generated for each of the resource blocks of the allocated interlacesbased at least in part on the reference signal symbols mapped to thatresource block.
 14. The apparatus of claim 11, wherein the processor isconfigured to generate the reference signals by: generating a number ofcomputer generated sequences; and mapping one of the computer generatedsequences to one of the resource blocks of the allocated interlaceswithin the contention based shared spectrum.
 15. The apparatus of claim14, wherein a length of the computer generated sequences is based atleast in part on a number of frequency subcarriers for the resourceblocks.
 16. The apparatus of claim 14, wherein the number of computergenerated sequences is based at least in part on the number of allocatedinterlaces.
 17. The apparatus of claim 14, wherein the processor isfurther configured to: shift at least one of the computer generatedsequences based at least in part on a random cyclic shift.
 18. Theapparatus of claim 14, wherein the processor is configured to map one ofthe computer generated sequences to one of the resource blocks by:generating an outer sequence; determining a number of combinedsequences, wherein the combined sequences are based at least in part onat least one of the computer generated sequences and the outer sequence;and mapping one of the combined sequences to one of the resource blocksof the allocated interlaces within the contention based shared spectrum.19. The apparatus of claim 11, wherein the processor is furtherconfigured to: transmit the uplink transmission over the computergenerated shared spectrum, wherein the uplink transmission comprises atleast one of the allocated interlaces.
 20. A method of wirelesscommunication, comprising: receiving at a user equipment (UE) a numberof interlaces allocated to the UE on a per-UE basis for an uplinktransmission over a contention based shared spectrum, wherein eachallocated interlace comprises a plurality of non-contiguous resourceblocks of the contention based shared spectrum in a carrier of afrequency domain; and generating reference signals for the resourceblocks of the allocated interlaces according to a reference signalsequence based at least in part on an ordering of the resource blocksfor the allocated interlaces within the contention based shared spectrumin the carrier of the frequency domain, wherein the ordering of theresource blocks comprises at least a lower-ordered resource block and ahigher-ordered resource block, wherein generating the reference signalscomprises mapping reference signal symbols from the reference signalsequence to the resource blocks of the allocated interlaces within thecontention based shared spectrum according to frequency, and wherein themapping comprises mapping the lower-ordered resource block beforemapping the higher-ordered resource block.
 21. The method of claim 20,wherein the contention based shared spectrum comprises a plurality ofresource blocks associated with at least one unallocated interlace,wherein the mapping further comprises mapping at least one unallocatedinterlace according to frequency; and the generating the referencesignals further comprises puncturing the reference signal sequence todetermine a subset of reference signal symbols mapped to the resourceblocks of the allocated interlaces, wherein a separate reference signalis generated for each of the resource blocks of the allocated interlacesbased at least in part on the reference signal symbols mapped to thatresource block.
 22. The method of claim 20, wherein generating thereference signals comprises: generating a number of computer generatedsequences; and the mapping further comprises mapping one of the computergenerated sequences to one of the resource blocks of the allocatedinterlaces within the contention based shared spectrum.
 23. The methodof claim 22, wherein a length of the computer generated sequences isbased at least in part on a number of frequency subcarriers for theresource blocks.
 24. The method of claim 22, wherein the number ofcomputer generated sequences is based at least in part on the number ofallocated interlaces.
 25. The method of claim 22, further comprising:shifting at least one of the computer generated sequences based at leastin part on a random cyclic shift.
 26. The method of claim 22, whereinthe mapping one of the computer generated sequences to one of theresource blocks comprises: generating an outer sequence; determining anumber of combined sequences, wherein the combined sequences are basedat least in part on at least one of the computer generated sequences andthe outer sequence; and mapping one of the combined sequences to one ofthe resource blocks of the allocated interlaces within the contentionbased shared spectrum.
 27. The method of claim 20, further comprising:transmitting the uplink transmission over the contention based sharedspectrum, wherein the uplink transmission comprises at least one of theallocated interlaces.
 28. An apparatus for wireless communication,comprising: a processor; and memory coupled to the processor, whereinthe processor is configured to: receive at a user equipment (UE) anumber of interlaces allocated to the UE on a per-UE basis for an uplinktransmission over a contention based shared spectrum, wherein eachallocated interlace comprises a plurality of non-contiguous resourceblocks of the contention based shared spectrum in a carrier of afrequency domain; and generate reference signals for the resource blocksof the allocated interlaces according to a reference signal sequencebased at least in part on an ordering of the resource blocks for theallocated interlaces within the contention based shared spectrum in thecarrier of the frequency domain, wherein the ordering of the resourceblocks comprises at least a lower-ordered resource block and ahigher-ordered resource block, map reference signal symbols from thereference signal sequence to the resource blocks of the allocatedinterlaces within the contention based shared spectrum according tofrequency, and wherein the mapping comprises mapping the lower-orderedresource block before mapping the higher-ordered resource block.
 29. Theapparatus of claim 28, wherein the contention based shared spectrumcomprises a plurality of resource blocks associated with at least oneunallocated interlace, and wherein the processor is configured togenerate the reference signals by: mapping reference signal symbols fromthe reference signal sequence to the resource blocks of the allocatedinterlace and the at least one unallocated interlace according tofrequency; and puncturing the reference signal sequence to determine asubset of reference signal symbols mapped to the resource blocks of theallocated interlaces; wherein a separate reference signal is generatedfor each of the resource blocks of the allocated interlaces based atleast in part on the reference signal symbols mapped to that resourceblock.
 30. The apparatus of claim 28, and wherein the processor isconfigured to generate the reference signals by: generating a number ofcomputer generated sequences; and mapping one of the computer generatedsequences to one of the resource blocks of the allocated interlaceswithin the contention based shared spectrum.
 31. The apparatus of claim30, wherein a length of the computer generated sequences is based atleast in part on a number of frequency subcarriers for the resourceblocks.
 32. The apparatus of claim 30, wherein the number of computergenerated sequences is based at least in part on the number of allocatedinterlaces.
 33. The apparatus of claim 30, and wherein the processor isconfigured to: shift at least one of the computer generated sequencesbased at least in part on a random cyclic shift.
 34. The apparatus ofclaim 30, wherein the processor is configured to map one of the computergenerated sequences to one of the resource blocks by: generating anouter sequence; determining a number of combined sequences, wherein thecombined sequences are based at least in part on at least one of thecomputer generated sequences and the outer sequence; and mapping one ofthe combined sequences to one of the resource blocks of the allocatedinterlaces within the contention based shared spectrum.
 35. Theapparatus of claim 28, wherein the processor is configured to: transmitthe uplink transmission over the contention based shared spectrum,wherein the uplink transmission comprises at least one of the allocatedinterlaces.